Denali third row question.

Hi I have a 2004 Denali XL and I was tailgating for a football game, and I took out the third row seat and used it as a bench in the parking lot. (Very nice). Then after I put it back in the Denali, I can no longer fold it down, and therefore take it out. Does anyone have any idea why this is, and/or how to remedy this situation? Thanks in advance. Tyler