If you remote desktop into the server without opening up SSMS, then try to issue the WSFTP command FROM WITHIN THE REMOTE DESKTOP, on the server - what happens?

Answer : If I Run the same command by REMOTE DESKTOP to the server and using command prompt it works perfectly .

Also - is your SSIS instance colocated with the database instance you're logging into, or is SSIS on a dedicated machine? as far as I know - WSFTP would have to be installed on the SSIS box (not the DB server one).

Answer: SSIS and sql server are on the same machine . WSftp is installed on this machine it self.