I am having some troubles with the boiler plate that I have just purchased. I am trying to bolt it up to my 185 Kessler with the UPM lower assembly. For some reason, the lower assembly will not bolt into all four of the holes on the board. It will only bolt into two bolts. My question is, is that correct for it to only bolt into 2 of the 4 bolts or should it be all 4?