There is no “root_user” for FAdmin, unless you have created a custom user group with inherited permissions. please try running the following command with rcon or from your server console.
FAdmin SetAccess **STEAM_0:1:1234567** superadmin
Make sure you replace the steamid field with your steamid. Also what version of DarkRP are you running? You can find this out by typing
It appears you’re using ULX due to the group you have for root, and FAdmin no longer collidies with ULX this was fixed many revisions ago. If you downloaded your installation from garrysmod.org or any other site besides the SVN Trunk. Please remove it and download from the following repository.