I just got a LF Substance and i am trying to screw the 2 added fins to it but the screws seem to be too big. I can only screw them in 3/4 of the way. is that possible? I feel that if i try harder i will break something. has this happened to anyone?

Get shorter screws.

is that the fins that came with the board? if so something is not adding up. there should be some nylon washers in there, are you using those. pics would help

You do NOT need fins on that board!

i think i had to add about 2 or 3 flat washers on mine. that would be the easiest and cheapest fix.

I had the same problem with my CWB when I got it. The fins were not drilled in deep enough. Get LF on the horn and have them send you a new set of fins. Tell them they were not drilled deep enough