Rear brakes on a '05 Chevy Tahoe?

[muskiemyke]

I've got a '05 Tahoe Z71. I'm doing my first brake job on it. (I actually made 101,000 miles on the original brakes. I do a lot of highway driving). I'm replacing pads and rotors. I got the fronts done without any problems (except for a couple of bolts that were incredibly tight). I got the first rear taken apart, got the new rotor on, put the caliper bracket back on. I'm putting the caliper bolts back in, and it seems like they screw into the top of the slide pins. How do you tighten them? I got them pretty snug, but the slide bolt spins before I can really lock it down. What's the secret?
Thanks for your help.