So I purchased the spoiler type tailgate cap for my 04 Silverado. The original was just the basic cap held on by 2 sided tape. The new one requires 4 nuts and bolts. I just went to put it on and found that the nuts (inserts) just slide into the tailgate holes and when you install the bolt, it doesn't tighten the spoiler down. You can wiggle the spoiler up and down and see the inserts just sliding in and out of the holes. What am I doing wrong?