Since upgrading to 2014 the mates folder has developed a mind of its own, it started when i tried to mate a new component, coincident, it refused, i deleted every mate in the assembly and still it claimed it couldnt, the mates folder showed an error despite being empty, i tried the mate expert and it showed a mate error on a mate which had been deleted, i clicked diagnose and it said "the mates folder has no errors, rebuild" rebuild has no effect, its now happening permanently in all assemblies, it shows the mate folder as having an error and when you enquire its a mate which no longer exists, the problem persists afetr saving closing restarting and rebooting.
cheers
I thought i should update this post with my workaround, just incase anyone else has this problem, Ive seen it on two machines now and ive tried a fresh install of the whole OS on my machine and whilst its less frequent its still a problem.
The problem occurs when your mates folder suddenly has an error which you cant understand, if you right click the mates folder and select mateExpert it should show an error, if you then click Diagnose it should say there are no problems and you should rebuild the assembly, if you then extend the lower box it will have a one or more mates listed, you then supress these mates and rebuild it should be fine, you will notice if your error is this error that none of the mates in your mates folder are suppressed, I dont know why solidworks is creating mates that it doesnt list in the mates folder and that cause the mates to be unable to find a solution, but the steps ive outlined have solved the problem for me every time.
Hope this helps someone.