I am having this same problem with the SVN ulib/ulx. It was working great before the latest gmod update that broke my dedi server, then the patch came out to fix that, and I could at least join my server, but now I get the [UCL] access set, so it's being read, but !menu or "ulx menu" does not work, and I get his error:
Lua initialized (Lua 5.1)
Registering gamemode 'fretta' derived from 'base'
Registering gamemode 'terrortown' derived from 'fretta'
TTT Client initializing...
Sending 10 'User Info' ConVars to server (cl_spewuserinfoconvars to see)
Welcome to [M4H] Trouble In Terrorist Town [24/7][UK][100 VANILLA]! We're playing ttt_cluedo_b5.
[UCL] Access set.
[UCL] Access set.
Hey '^2[m4h]^0kccool2' - You're in the 'superadmin' group on this server.
[UCL] Access set.
TTT Client post-init...
Redownloading all lightmaps
YOUR KARMA IS 1100, AS A RESULT YOU DEAL FULL DAMAGE THIS ROUND!
A NEW ROUND BEGINS IN 30 SECONDS. PREPARE YOURSELF.
Round state: Preparing...
] ulx menu
] ulx
^2[M4H]^0Kccool2: !menu
Warning: Unhandled usermessage 'ULibLuaFn'You are playing Trouble in Terrorist Town, version 13-06-10 (13th of June, 2010).
You are: TRAITOR
I am in desperate need of help! Please guys!

And this IS with the SVN's of BOTH ULX and Ulib. It also does the same thing with the release versions, not just SVN. I'm so confuddled as I see other TTT servers using ULX just fine..
I've tried re-installing loads of times, just the same thing.