i dont see any problems , when i use WinCSP GUI client to download a file its working without problems , so what is the different between GUI and CLI ?
That's irrelevant. Your server misbehaves, that's the problem.
Anyway to answer your question: If you do
get 2.bmpin the script, it needs to find out the file attributes (Is it a file or folder? What is its timestamp?) WinSCP can use several commands for that and it picks the command that the server claims to support. That's where you server fails. In GUI, WinSCP knows the file attributes from a directory listing (retrieved using different command). That part works on your server. If you do something like
get *.bmpor even
get 2.bmp*, it would work as the scripting will use the same commands as GUI.