Core FTP

I have a server on our network setup with Core FTP server and it is behind a firewall. I have ftp open on port 21 on the external address as I need users outside of our company to use this. It seems to get to the server when I type the address in but I am receiving an access error. The error is a Core FTP server error, but it says 504 ssl connection required. I do not have the "force ssl" checked in core ftp server. Do I need to add another conduit statement to the pix router for ssl? Anyone that could point me in the right direction would be great.

Thanks, Scott...