Error 127, unable to find an existing file

Hello,

I'm using WinScp to doawnload files from remote unix hosts to my NT computer. Till now it has worked properly. But today i'm dealing with a problem that occurs for the first time : a "can't command fail with return code 127.Unable to copy file. Can't find file".
I'm sure the file is on the remote host and i can download it using command lines.
Neither could i upload files.
can you help fixing the problem

SCP comand is probably not in path on your server. Check your server configuration or use SFTP instead of SCP.

Please read documentation for possible reasons for getting the error.