The following isn't the correct way to diagnose the problem, but...
What I like to do (especially when I'm not the original designer of the part/assembly) - what I like to do is 'blow away all the mates.' Go to the 'mates' - then just delete them all - or suppress them one by one. In that way it's easy to troubleshoot your part a little better.
SW Professional 2014 SP 5.0
SW Electrical 2D/3D SP 5.0
64 bit
Intel Xeon X(R) CPU 1603 0 @ 2.80 GHz
8.0 GB of RAM
NVIDIA Quadro 2000