HE rounds destroy it. But AP rounds shouldn't go through a truck..
Now, there might still be an issue that the truck OUGHT to be destroyed or at least taken out of commission when hit by an AT round on the front, but at least you'd have a better sense of where the problem lies.
Regardless, light vehicles you're better off using HE anyway. In real life, that's what you'd have done, since an AP round could conceivably go through the vehicle without actually destroying it.