How to get a good suction with banana prosthetics hard packer?

This might have been asked before but I genuinely can't find anything. I ordered the hp 4, and yeah, holy cow, it's huge lol. I don't mind the size but we'll see how my girlfriend minds it. Anyways, I'm having some issues getting a good suction. I probably just need more practice but I figured I would ask just in case. Basically, how I'm doing it is like a weird mixture of shoving my t-dick into the hole while pushing on the balls to get the air out. It kinda works, but I don't really get much sensation when masturbating, it just kinda feels like someone's grabbing my dick and wiggling it around. It has to be the suction, I've had this similar issue with my stroker and I fixed it by getting a better suction. Anyways, do you guys have some tips and tricks on how to use the hard packers?