Can swim-regions conflict with other regions?

I had trouble with my sittingmod-regions and I tried about evrything to make them work. The alscript was ok, also the object it self, checked and checked. And in the end I started to take away things added later,( you know the drill
) and after removing the swim-region they worked! So now I don't make that big swim-regions any more
But it would be nice to know for sure?


But it would be nice to know for sure?