The trainers from CH are not for MP/COOP/MMO they are SP only. They are only desgined for SP. Plus these statements are taken from the TOS and FAQ.
We do not make cheats for online or multiplayer games and never have.
Q: Why aren't there any cheats for multiplayer games or modes on your site?
A: CHEAT HAPPENS does not support or condone the use of cheats in a multiplayer environment
Take a look at the event viewer of Windows. Look out for a trainer crash entry or a .NET crash entry which fits to the time you started the trainer. If there is none then the trainer is likely getting killed by a security software.