I got a question about the Bolt on the CAM.

Hi, I got a question about the bolt on the cam bearing caps. We broke a bolt on one of the caps installing it. It's torque is 14.5 LBS, we did it in stages and bolt pattern. First was 10 LBS then 14.5 LBS. When torquing it the second time one of the bolts didn't feel like it was tighten correctly. It felt like the threads where slipping, I couldn't get it to torque at 14.5 LBS. When I was doing it I was going slow like your suppose to. I would pull a little and stop, it felt like it wasn't getting any tighter. I did it several time and then the bolt broke. This isn't my first time torquing something down and I have a pretty new torque wrench. Now I was wondering does all the bolts (have) or should be replaced on the cam caps, because if the threads were slipping then bolt wouldn't have broke. Was also wondering if the bolts are stressed. I tried to bolt the cap on the other one head before we put the head on and the same thing was happing. It seems like it's the front caps only, might be coincidence. Would appreciate any info. Thanks, jason