if you have the same problem I had, its because the Jayco factory wizards used screws WAY too long to hold the hose adapter to the vacuum body.
Look inside where your trying to push the bag onto and see if there are two screws sticking sharp end out an inch or more... that is stopping the bag from being pushed on farther.
I'm pretty sure the screws should be going the opposite way and not be in the way or at least very short, if they insist on the pointy end cutting your fingers.
2016 North Point 341RLTS
2012 F-350 Lariat CC SRW