for people who can't make this work, here are some solutions :
1. your anti-virus is blocking/deleting trainers (not just this) - first off, create a folder dedicated for your trainers - then excluded the folder from scans via your anti-virus settings - i don't use AVG Free as it doesn't have this feature - i use NOD32 but anything with an "exclude folder from scans" feature will work as well
2. some of MAF's trainers needs sometime to activate - for the ones that need activation, wait for the "trainer activated" voice upon pressing F1 - if you hear a ping, that means you got the wrong trainer for your game's version - as for activating cheats themselves, wait for the "cheat activated" voice - activating cheats do take a while on some games - you can check on the trainer by alt+tab-ing, if your game supports multi-tasking - if you hear a ping instead, check the front page of the trainer's thread for activation notes for that specific cheat - that ping means that you have to do something before activating that cheat like dispensing some items or firing your gun to lessen your in-chamber/magazine ammo count before activating an infinite item(s) or infinite ammo cheat
3. as for the Skills cheat, i admit i made the mistake of going to the Skill Equip - Skill List is within Player Data - you must activate the cheat then go to Player Data then go to Skill List - take note that you must go into the Skill List before you could equip cheat unlocked skills otherwise they will not be listed in Skill Equip