In 2015 if you try to create a mate, that for any reason wont work, SW gives you an error saying that this mate cannot be solved, and then it gives you an option to force it.  Even if you select NO to this, SW still puts in the mate and your whole damn assembly turns red, yellow and everyother jaundice colour there is.  Why when you SAY NO, doesnt this get recognized?

SW never used to do this in previous versions - this is a pain in the ass to have to constantly delete the offending constraints.  they are easy to see, but it shouldn't be necessary.

The SW programmer that changed this feature - needs a new job - give him a broom, something that he can handle.....