are you using the ntsc version of the game?
There is one known ntsc xbe, and two pal xbe's. There are several 'revisions' of the trainer, if you are a pal user that its not working for, post a message here and I'll work with you to determine if you have the proper version of the trainer.. I only posted the ntsc and the first pal version on the normal trainer sites, and xbins, but I will post the one I did for one specific person that was having problems if others actually need it. (the last version actually does every version but I limited distribution to decrease confusion on the trainer sites, people are still downloading the +1 version of the trainer instead of the latest one)
Anyone with gripes or questions involving other trainers I did feel free to start a thread of pm me.