I cannot get the disposal to attach to the drain.  The aluminum mount ring will not slip over the cushion mount once installed on the sink flange no matter what I do I can get the disposer to connect to the mounting ring.  I cannot get the mounting ring to turn.  I have tried about 10 times and and I may possibly have the wrong flange for the GFC1020N.

Anyone else have this problem?  Or can I get the correct sink flange?