Insert the top of the PEX more than the tip in the fitting. Slide the end from the PEX tubing that has the crimp ring or cinch clamp on it more than the top of the fitting which you screwed on to the copper tubing. Thrust it on so far https://eartreatmenttips43095.onzeblog.com/32101226/5-simple-techniques-for-copper-female-adapter