Activate the trainer ingame, make sure you're not directly at the beginning of the campaign (where you have no weapon). Listen for the SECOND trainer activated sound.
sadly this does not solve the problem I'm having. as soon as i activate the trainer in the campaign or a scenario the game crashes. the trainer itself does not crash.I also sometimes get a .Net error but I have installed .Net3.5 and .Net4
since the trainer is older(as far as I can tell) than the latest version of the game could this be the cause?
You sure about this? I've tested everything and this update works for me. The infinite health option isn't perfectly but as descripted, it's related to the way the game has been coded. Could you test for example infinite jetpack ?