Garrys Mod server updating!

I have a Gmod Server. On this server i play TTT with friends. We tried to play today but the server says he have a too old version.
I tried to update him with the SteamCMD (app_update 4020 /validate /over installed) and it doesnt worked.
Now to my question, can it be that the servers are not updatet yet but the clients are ? Because i cant update the server, but i can update our clients!

SIEG HEIL!

Reinstall the server to a new directory, then move all of your custom content over.

Thank you it worked!

type update

type quit smokinbg for good update hobo lobo