Ball IT sleeve? Didn't know the IT system had a sleeve . .
The main problem is getting the stem in the bottom of the ball IT completely seated. There's a rod that goes down the middle of the insertion tool to tap on to make sure the stem is fully seated. If it's not and is raised up at all, the bottom of the slug will rub on it and may not even click. I put the rod in the insertion tool when I'm screwing on the ball IT and use it to hold the stem down while I'm putting it in the ball, because even if you have it seated before you insert it, the hole is still tight enough that it might force the stem up a little.
The other thing is at the top of the hole. Once I glue the collar in at the top of the hole, I always take the sander to it to smooth off the ridges and open it up a bit.