Executing OS-Command

Hi experts,

I would like to execute the following OS statement, for moving files.

"mv /dir/file /dir/archive/file"

The command runs perfect via telnet on the server.

But when I execute the same via SM69 or program code "call system id command..." I always get the following error message:

"Can't exec external program (No sucha file or directory). External program terminated with exit code 1"

Our OS is HP-UX.

Any ideas, how I can execute the statement on the server via sap?

thx in advance