How can I put a sleeve into the frame of a paint roller?

Its a new set with 2 sleeves, the furry ones, there is a round plastic at one end which I assume I have to remove before pushing the sleeve in, but no matter how hard I pull,twist,push, the plastic refuse to budge, help!How can I put a sleeve into the frame of a paint roller?
no don't try and get the plastic off you push the sleeve over the whole lot.How can I put a sleeve into the frame of a paint roller?
the plastic plastic piece is the outside the open end slides onto the roller then the plastic end keeps it straight
You don't remove the plastic end, the sleeve should push on over it.