No signing table match for <user@gmail.com> in OpenDKIM configuration

I have follower this tutorial.
I have a problem with my opendkim configuration. I have the alias ciao@mrtsolutions.it that forward all to mymail@gmail.com. When I send email to alias ciao@mrtsolutions.it from me@mrtsolutions.it, I correctly receive the mail in mymail@gmail.com, but if i send an email from an external domain (user@gmail.com) to alias ciao@mrtsolutions, i can't receive the mail in mymail@gmail.com.

When I send from internal:

May 17 11:53:44 server postfix/smtpd[25525]: connect from localhost[127.0.0.1]
May 17 11:53:44 server postfix/smtpd[25525]: 629403F011: client=localhost[127.0.0.1]
May 17 11:53:44 server postfix/cleanup[25528]: 629403F011: message-id=64dc25b5c034c5ce4e9660e32584a687@mrtsolutions.it
May 17 11:53:44 server opendkim[25876]: 629403F011: DKIM-Signature field added (s=mail, d=mrtsolutions.it)
May 17 11:53:44 server postfix/qmgr[29019]: 629403F011: from=lorenzo.martini@mrtsolutions.it, size=14306, nrcpt=1 (queue active)
May 17 11:53:44 server spamd[17463]: spamd: connection from ::1 [::1]:57908 to port 783, fd 5
May 17 11:53:44 server spamd[17463]: spamd: setuid to spamd succeeded
May 17 11:53:44 server spamd[17463]: spamd: processing message 64dc25b5c034c5ce4e9660e32584a687@mrtsolutions.it for spamd:5555
May 17 11:53:44 server spamd[17463]: dns: new_dns_packet: domain is utf8 flagged: ns17.ovh.net
May 17 11:53:44 server spamd[17463]: dns: new_dns_packet: domain is utf8 flagged: dns17.ovh.net
May 17 11:53:46 server dovecot: imap-login: Login: user=lorenzo.martini@mrtsolutions.it, method=PLAIN, rip=149.202.56.54, lip=149.202.56.54, mpid=25532, TLS, session=<gfa0wxkj1pgvyjg2>
May 17 11:53:46 server postfix/smtpd[25525]: disconnect from localhost[127.0.0.1] ehlo=1 mail=1 rcpt=1 data=1 quit=1 commands=5
May 17 11:53:46 server dovecot: imap(lorenzo.martini@mrtsolutions.it): Logged out in=14171 out=658
May 17 11:53:46 server spamd[25533]: util: setuid: ruid=5555 euid=5555 rgid=5555 5555 egid=5555 5555
May 17 11:53:46 server spamd[17463]: spamd: clean message (0.7/5.0) for spamd:5555 in 2.0 seconds, 14405 bytes.
May 17 11:53:46 server spamd[17463]: spamd: result: . 0 - ALL_TRUSTED,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HTML_IMAGE_ONLY_08,HTML_MESSAGE,URIBL_BLOCKED scantime=2.0,size=14405,user=spamd,uid=5555,required_score=5.0,rhost=::1,raddr=::1,rport=57908,mid=64dc25b5c034c5ce4e9660e32584a687@mrtsolutions.it,autolearn=no autolearn_force=no
May 17 11:53:46 server postfix/pipe[25529]: 629403F011: to=ciao@mrtsolutions.it, relay=spamassassin, delay=2.2, delays=0.08/0.02/0/2.1, dsn=2.0.0, status=sent (delivered via spamassassin service)
May 17 11:53:46 server postfix/qmgr[29019]: 629403F011: removed
May 17 11:53:46 server postfix/pickup[24507]: 850873F013: uid=5555 from=lorenzo.martini@mrtsolutions.it
May 17 11:53:46 server postfix/cleanup[25528]: 850873F013: message-id=64dc25b5c034c5ce4e9660e32584a687@mrtsolutions.it
May 17 11:53:46 server opendkim[25876]: 850873F013: DKIM-Signature field added (s=mail, d=mrtsolutions.it)
May 17 11:53:46 server postfix/qmgr[29019]: 850873F013: from=lorenzo.martini@mrtsolutions.it, size=15090, nrcpt=1 (queue active)
May 17 11:53:46 server clamsmtpd: 10002B: accepted connection from: 127.0.0.1
May 17 11:53:46 server spamd[17452]: prefork: child states: II
May 17 11:53:46 server postfix/smtpd[25538]: connect from localhost[127.0.0.1]
May 17 11:53:46 server postfix/smtpd[25538]: AD3F63F011: client=localhost[127.0.0.1]
May 17 11:53:46 server postfix/cleanup[25528]: AD3F63F011: message-id=64dc25b5c034c5ce4e9660e32584a687@mrtsolutions.it
May 17 11:53:46 server opendkim[25876]: AD3F63F011: DKIM-Signature field added (s=mail, d=mrtsolutions.it)
May 17 11:53:46 server postfix/qmgr[29019]: AD3F63F011: from=lorenzo.martini@mrtsolutions.it, size=15689, nrcpt=1 (queue active)
May 17 11:53:46 server clamsmtpd: 10002B: from=lorenzo.martini@mrtsolutions.it, to=ciao@mrtsolutions.it, status=CLEAN
May 17 11:53:46 server postfix/smtp[25536]: 850873F013: to=ciao@mrtsolutions.it, relay=127.0.0.1[127.0.0.1]:10026, delay=0.39, delays=0.06/0.03/0.08/0.22, dsn=2.0.0, status=sent (250 2.0.0 Ok: queued as AD3F63F011)
May 17 11:53:46 server postfix/smtpd[25538]: disconnect from localhost[127.0.0.1] ehlo=1 xforward=1 mail=1 rcpt=1 data=1 quit=1 commands=6
May 17 11:53:46 server postfix/qmgr[29019]: 850873F013: removed
May 17 11:53:47 server postfix/smtp[25540]: AD3F63F011: to=lorenzomartini123@gmail.com, orig_to=ciao@mrtsolutions.it, relay=gmail-smtp-in.l.google.com[74.125.140.27]:25, delay=0.69, delays=0.22/0.02/0.11/0.34, dsn=2.0.0, status=sent (250 2.0.0 OK 1558086827 k12si6047671wru.260 - gsmtp)
May 17 11:53:47 server postfix/qmgr[29019]: AD3F63F011: removed</gfa0wxkj1pgvyjg2>

And when I send from external (example from gmail):

May 17 11:57:29 server postfix/smtpd[25644]: connect from mail-it1-f172.google.com[209.85.166.172]
May 17 11:57:30 server policyd-spf[25649]: prepend Received-SPF: Pass (mailfrom) identity=mailfrom; client-ip=209.85.166.172; helo=mail-it1-f172.google.com; envelope-from=lorenzomartini123@gmail.com; receiver=<unknown>
May 17 11:57:30 server postfix/smtpd[25644]: 17B713F011: client=mail-it1-f172.google.com[209.85.166.172]
May 17 11:57:30 server postfix/cleanup[25650]: 17B713F011: message-id=<caayxrvby-mzhhgvqc=2fm3p9djtypzs9vzdan63papngpp6brg@mail.gmail.com>
May 17 11:57:30 server opendkim[25876]: 17B713F011: mail-it1-f172.google.com [209.85.166.172] not internal
May 17 11:57:30 server opendkim[25876]: 17B713F011: not authenticated
May 17 11:57:30 server opendkim[25876]: 17B713F011: DKIM verification successful
May 17 11:57:30 server opendkim[25876]: 17B713F011: s=20161025 d=gmail.com SSL
May 17 11:57:30 server postfix/qmgr[29019]: 17B713F011: from=lorenzomartini123@gmail.com, size=3257, nrcpt=1 (queue active)
May 17 11:57:30 server spamd[17463]: spamd: connection from ::1 [::1]:57968 to port 783, fd 5
May 17 11:57:30 server spamd[17463]: spamd: setuid to spamd succeeded
May 17 11:57:30 server spamd[17463]: spamd: processing message <caayxrvby-mzhhgvqc=2fm3p9djtypzs9vzdan63papngpp6brg@mail.gmail.com> for spamd:5555
May 17 11:57:30 server postfix/smtpd[25644]: disconnect from mail-it1-f172.google.com[209.85.166.172] ehlo=2 starttls=1 mail=1 rcpt=1 data=1 quit=1 commands=7
May 17 11:57:31 server spamd[25653]: util: setuid: ruid=5555 euid=5555 rgid=5555 5555 egid=5555 5555
May 17 11:57:32 server spamd[17463]: spamd: clean message (-0.1/5.0) for spamd:5555 in 1.8 seconds, 3323 bytes.
May 17 11:57:32 server spamd[17463]: spamd: result: . 0 - DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,HTML_MESSAGE,SPF_PASS scantime=1.8,size=3323,user=spamd,uid=5555,required_score=5.0,rhost=::1,raddr=::1,rport=57968,mid=<caayxrvby-mzhhgvqc=2fm3p9djtypzs9vzdan63papngpp6brg@mail.gmail.com>,autolearn=ham autolearn_force=no
May 17 11:57:32 server postfix/pipe[25651]: 17B713F011: to=ciao@mrtsolutions.it, relay=spamassassin, delay=2.4, delays=0.62/0.02/0/1.8, dsn=2.0.0, status=sent (delivered via spamassassin service)
May 17 11:57:32 server postfix/qmgr[29019]: 17B713F011: removed
May 17 11:57:32 server postfix/pickup[24507]: 325873F013: uid=5555 from=lorenzomartini123@gmail.com
May 17 11:57:32 server postfix/cleanup[25650]: 325873F013: message-id=<caayxrvby-mzhhgvqc=2fm3p9djtypzs9vzdan63papngpp6brg@mail.gmail.com>
May 17 11:57:32 server opendkim[25876]: 325873F013: no signing table match for 'lorenzomartini123@gmail.com'
May 17 11:57:32 server opendkim[25876]: 325873F013: DKIM verification successful
May 17 11:57:32 server opendkim[25876]: 325873F013: s=20161025 d=gmail.com SSL
May 17 11:57:32 server postfix/qmgr[29019]: 325873F013: from=lorenzomartini123@gmail.com, size=3826, nrcpt=1 (queue active)
May 17 11:57:32 server clamsmtpd: 10002C: accepted connection from: 127.0.0.1
May 17 11:57:32 server spamd[17452]: prefork: child states: II
May 17 11:57:32 server postfix/smtpd[25658]: connect from localhost[127.0.0.1]
May 17 11:57:32 server postfix/smtpd[25658]: 5A3193F011: client=localhost[127.0.0.1]
May 17 11:57:32 server postfix/cleanup[25650]: 5A3193F011: message-id=<caayxrvby-mzhhgvqc=2fm3p9djtypzs9vzdan63papngpp6brg@mail.gmail.com>
May 17 11:57:32 server opendkim[25876]: 5A3193F011: no signing table match for 'lorenzomartini123@gmail.com'
May 17 11:57:32 server opendkim[25876]: 5A3193F011: DKIM verification successful
May 17 11:57:32 server opendkim[25876]: 5A3193F011: s=20161025 d=gmail.com SSL
May 17 11:57:32 server postfix/qmgr[29019]: 5A3193F011: from=lorenzomartini123@gmail.com, size=4061, nrcpt=1 (queue active)
May 17 11:57:32 server clamsmtpd: 10002C: from=lorenzomartini123@gmail.com, to=ciao@mrtsolutions.it, status=CLEAN
May 17 11:57:32 server postfix/smtp[25656]: 325873F013: to=ciao@mrtsolutions.it, relay=127.0.0.1[127.0.0.1]:10026, delay=0.4, delays=0.06/0.03/0.08/0.24, dsn=2.0.0, status=sent (250 2.0.0 Ok: queued as 5A3193F011)
May 17 11:57:32 server postfix/smtpd[25658]: disconnect from localhost[127.0.0.1] ehlo=1 xforward=1 mail=1 rcpt=1 data=1 quit=1 commands=6
May 17 11:57:32 server postfix/qmgr[29019]: 325873F013: removed
May 17 11:57:32 server postfix/smtp[25660]: 5A3193F011: to=lorenzomartini123@gmail.com, orig_to=ciao@mrtsolutions.it, relay=gmail-smtp-in.l.google.com[64.233.184.26]:25, delay=0.63, delays=0.24/0.02/0.2/0.17, dsn=2.0.0, status=sent (250 2.0.0 OK 1558087052 r193si6247994wmf.54 - gsmtp)
May 17 11:57:32 server postfix/qmgr[29019]: 5A3193F011: removed</caayxrvby-mzhhgvqc=2fm3p9djtypzs9vzdan63papngpp6brg@mail.gmail.com></caayxrvby-mzhhgvqc=2fm3p9djtypzs9vzdan63papngpp6brg@mail.gmail.com></caayxrvby-mzhhgvqc=2fm3p9djtypzs9vzdan63papngpp6brg@mail.gmail.com></caayxrvby-mzhhgvqc=2fm3p9djtypzs9vzdan63papngpp6brg@mail.gmail.com></caayxrvby-mzhhgvqc=2fm3p9djtypzs9vzdan63papngpp6brg@mail.gmail.com></unknown>