In looking at them, I noticed a scre right in the middle of the two brackets. Is that to be unscrewed and then re-screwed into the T bracket that I'll mount them to the wall to? I placeed the T braceket on the speaker, and it doesnt' look like it lines up w/ a hole on the bracket once it's slid into place. Or does that screw not have anything to do with the bracket and just leave it alone?