I had the trainer active and was able to kill the tanks on the bridge with the javelin. The game tells you to do it from the second floor. Also it's important to note that the javelin's firing arc is not direct line-of-sight. It goes up in the air and comes down on the target.
You have to right click and use the aiming sight. Aim at the tanks and a target lock indicator and tone will tell you when to fire.
[Edited by flerndip, 11/8/2007 4:38:23 PM]
Thanks! I though the trainer just doesn't work on that particular level. I'll fire up the game and report back...