FTP Error Code 600

Dear All
recently I met with an issue that when our webmethods’ procedure trying to login FTP site ,it returns 600.
I searched in google website,but cann’t find FTP return code for 600.So I wander if this return code is for webmethods only and what this return code means. Could anyone help me out of this problem,thank you very much!

What is that you were trying to accomplish, can you please be more specific with respect to the task you were trying to accomplish with respect to ftp.