Diff support bolts wont tighten??

Installing my diff drop right now and i got the spacers in BUT the support bolts wont tighten. Im using a box end wrench to hold the nut and a socket to spin the bolt but the bolt will turn about two rotations and it will "click" and will never tighten up. Is this odd or am I just doing something completely wrong?

 

Nope, I really have no idea why this is happening. I'm using all of the hardware that came in my toytec kit. doing everything like the instructions say.

 

I had installed a drop kit I got from TOYTEC,had the same problem. I had to go to ACE hardware and buy new bolts with the correct thread pitch.