Looks like FTP commands became case sensitive in Windows NT 3.1. See mskb #Q112421 Err Msg: ?Invalid Command with FTP and CAPS LOCK On.

>The FTP software we're using is the FTP command set that comes with Windows. If you go to a command window and type in fpt(enter) then type in help(enter) you'll see them. They are run from the command line or batch files just like DOS commands. We are ftp'ing ASCII files to an AS400.
Err Msg: ?Invalid Command with FTP and CAPS LOCK On