Yeah two of the ones that dont screw in have risers in them.. The screws i screwed in were too big and when i pulled them out the riser was stuck on the screw... Its no big deal, theres just a little gap there now..
I did the same thing beleive it or not, when fitting mine.
Luckily for me, the right screws still screwed in tight, with a little push.
Make sure the board is touching the riser, and then try to do it again.