CP translation files

Hi,
I have translated the lang files in CP plugin folder (cp-default.mo + po) to hebrew, i saved the files with -he_IL (cp-default-he_IL.pot and the compiled one as cp-default-he_IL.mo.
WP is set to Hebrew but it's not working and the Eng one is loaded and not the hebrew one...
Am I missing something?
Thanks,
Amir