copy disk over ssh, Unknown command 'dd if=/dev/xvda'

guys, I followed this tutorial ~~[http://library.linode.com/linode-platform/migration/copy-disk-image-over-ssh" target="_blank">](http://library.linode.com/linode-platfo … e-over-ssh">http://library.linode.com/linode-platform/migration/copy-disk-image-over-ssh](

and when I run the command

ssh root@12.34.56.78 "dd if=/dev/xvda " | dd of=/home/archive/linode.img

I get a 1KB file on my PC named linode.img, when I open that file I find this text: Unknown command 'dd if=/dev/xvda'

What could be the problem?