Firstly, the screw problem is not uncommon. A friend's Signal has the same issue. Try tightening each screw 1/4th of the way in to get them started, then go corner to corner tightening. They'll all go in.
If you tighten one all the way down, it'll pull the binding up from the board and the base plate will not be positioned correctly.
it seems as if the thread on the board is stripped. all of the other screws are in tight. this one you can turn and turn and it just doesnt catch. i tried a couple of different screws. i just rode it with 3 screws instead of 4 and it was sturdy, but its new and shouldnt be defected. ill try taking them all out and redoing it.