Hi all,

Here is a really annoying problem that has only struck recently, and I have no idea why. 

In my master scheme I have two sub assemblies and eight bolts (non toolbox parts).  If I click on the first sub assembly then >mass properties I get the mass properties of that sub assembly, same with the second sub assembly and same with the bolts.  But when I select the top level master scheme I get the following message:

This happens when I select the first and second sub assemblies too and also a sub assembly and a bolt, so more than one thing and it falls over.  I cant find the problem because they all work individually.

Yes I have tried Ctrl-Q and rebuilt the assembly many times over.  I have no broken references either. 

Your help would be appreciated. 

Rob.