When doing a screw mate selecting inner surface of the bolt and outer surface of nut making PM active (first picture). But selecting outer surface of bolt and inner surface of the nut making PM not active (second picture).
What is the reason for that?
First picture
Second picture
The inner surface of the bolt and outer surface of the nut are circular surfaces that were created before the threads were created. The outer surface of the bolt and inner surface of the nut were created using the thread feature (fancy sweep using a helix as the path). Due the nature of the way the thread feature is created the outer bolt surface and inner nut surface are not recognized as a circular surface (analyze the surfaces using the measure tool and you will see the difference) thus cannot be used to create a screw mate. Hope this explanation makes some sense?