"access denied!"

I just got my server and wanted to install ASS Mod.
I got ASS mod on the server and sat me as superadmin in the Gmod/Gmod/settings/users.txt file.
But when i try to use the console command “ASS_GiveOwnerShip (My Number)” It just says “ACCESS DENIED!”.
Ive tried looking for a answer all night long, but couldnt find anything. What can i do to get admin privileges?

You have to do that on the server, not your client.

In other words, run these commands:

rcon_password <your rcon password>
rcon <the assmod command>