H3T Extang Trifecta Install

[hummer.dad]

I just received an Extang Trifecta cover, but the clamps will not pull down far enough to attach to the tie down rails. Does anyone have one of these installed? If so, how did you install it? Supposed to be the easiest covers, but I wonder if that is true for the H3T. Any help would be greatly appreciated. I will be calling Extang on Monday to see what they say. I would rather get real life feed back though.