Cheat Engine Addresses Help! Please.

Hey guys recently i've been trying to get my head together and make some CE trainers for L4D2 example, and when i've found the address for Health and freeze it, it works (online). But when im going for ammo i only seem to get one gun and that is the gun im trying to freeze for example the AK-47 that is the only gun with inf ammo. What am i doing wrong? I might look stupid to some about this but i want to learn i've done the tutorials in CE but i still quite dont understand...

Please help.