KRose - DreamPort is compatible with any tube and cpap unit on the market. More than likely your previous mask has a swivel that's lodged inside the tubing and you will have to remove that. Did you previously use the DreamWear mask? It's notorious for the the slip ring doing that. The easy quick check for this situation is squeezing the end of the tubing, along the rubber wall. If it does NOT collapse flat when you squeeze it, then something is inside and needs to be removed. Normally, with the Dreamwear mask, it's a white ring you will see. Text me a picture of the opening of the tube, if you have not solved this. Thank you.