Error 501- Unknown extension in database file name

Hi,

When trying to FTP a text file from local desktop to IBM i getting error
'Unknown extension in database file name.'

just before 22 PORT subcommand request successful.
and then suddenly above error.

I was able to login to the server and was able to to quotesite namefmt 1
lcd c:\temp
LCD directory now C:\Temp

ftp>cd /QSYS.LIB/Mylib.lib
250 "/QSYS.LIB/Mylib.lib" is current library.
ftp>put mytextfile.txt mysoyrcefile.mytextfile (replace
200 PORT subcommand request successful.
501 Unknown extension in database file name.


Any suggestions to resolve this error please?

Thanks much..