mates gone wild

I am in an assembly

I am using virtual components.

I create a mate everything is good. It accepts it.

I exit the mate command feeling OK, even good.

Then the mate constraint doesn't even hold. ITs like I never created the mate.

This isn't the first time this has happened. This needs to be looked at.

Its aggravating to say the least.

SolidworksAssemblies