Right, plus there is absolutely no way to get that error message (you do not have access) if you used the dedicated console. If you do not have access to it (you buy your server) then try getting a program like HLSW, it's what I use and I LOVE it.
or, alternatively, you can type rcon_password YOURRCONPASSWORD
in your GAME console, and then type 'rcon' before the command you wish to run on the server console.
This will work
You will need to be in game and connected to your server for this to work...
rcon_password <your RCon Password Here> If you dont know it, look in your config file or contact your server provider.
rcon ulx adduser <your name> superadmin
after you are added as super admin, you can then use your game console to add other people.