Hi, I need some advice about a leak. I recently had a leak from the underground stop cock for mains water, so replaced it with a new one. The problem I have now is that the mdpe pipe is quite loose at the compression tee, I can't get the nut to tight enough for the olive to clamp properly on the pipe. The pipe does have a insert, I've tried using a new olive and a used one that was in good condition. I'm wondering if it has something to do with the diameter of old black pipe vs new blue pipe.