FTP.Syntax.Error | CVE-2011-0507

Hi There, 

An Alert named: "FTP.Syntax.Error", is  constantly seen on our network. After verification, it is a known FTP Traffic. I also did packet capture for this, but the traffic seems okay, all successful response codes were seen; nothing unusual.

The FTP Firewall policy is also on allow; so the traffic can easily go to and fro.

But, still we see alot of ftp.syntax.error alerts; i.e around 300K WEEKLY.

Which is alot, anyone here can help me regarding this?

Would be really appreciated.

Thank you.