[Edited by show, 2/23/2009 7:28:18 PM]
Problem source: when using unlimited Ammo option on trainer, Check the number of ammo your soldier has.
Solution : either don't use ammo option, or just drop the ammo you have then pick up weapon from ground and pick up ammo again then reactivate ammo option.
I hope this help
had a loser in the first mission with a pistol and wanted him to pick up a LMG, however he just wouldn't listen to me until I had him sit aboard the KV1, hop right back off, and he picked it up without a second's hesitation.
Now keep in mind, the game itself is dubiously programmed, and the voice acting is enough to make the original Resident Evil worthy of an Oscar in comparison, but the work-around seems to have done the trick for me, so hopefully it's a real solution for others.