I am guessing you have just started.
Rabbits will sometimes hold fast in the hole when they have turned around at the entrance, and when you try to pull them out, they block them selves in because the body bends in the hole, i.e. becomes bigger in size because they are almost folded.
If it was in a net properly it can be because it has gone back down, and gone around a corner, again you are pulling it out at an unusual angle, which can be harder.
The rabbit will squeel either in pain, in fear, or because it is a kit.
Gently pull the ferret off the rabbit to release it, by slowl