If your sure all parts are correct and in correct alignment then you may have to do what I did some 20 years ago.
Get two bolts about a 1/4 in longer then the stock bolts.
put one in one hole and on opposite side the other. Turn them in just enough to get the plate lined up and started down until your stock bolts threads grip. Then put in the stock bolts and once all but the two are in remove the two longer bolts and replace with stock.
DO NOT LEAVE in longer bolts. MAKE SURE all is correctly aligned.
