Can you confirm that you are running VOSS and not EXOS on your 5420 ?
How are you connected to the terminal ? remote SSH ? console port ? OOB port ?
Check this part to be sur to not be filtered by any access policy (#show access-policy) or any ACL.
Then, if it's VOSS, you need to enable the ftp deamon through the boot flag.
(config)#boot config flags ftpd //You can check it with "show boot config"
for more diag, please share config, full tech and setup details about FTP client/server.