In-sink-erator leaking

My dad and I are replacing the in-sink-erator in our kitchen sink, and the T pipe that connects the two halves of the sink is leaking from a rubber gasket. We replaced the gasket and added some plumber's putty to help stop it, but it still drips. We've tightened the screws as much as we feel safe with, any ideas on how to stop it?

This is what's leaking. My dad removed the gasket before I could get the picture, but it was in between the lip of the pvc pipe and the metal washer with the screw holes. Any and all help is appreciated greatly!

EDIT

Okay so apparently the gasket goes before the pipe? The discharge hole on the erator is square shaped so we just moved some things around, put the gasket on, then the pipe, then tightened the compressor washer down and it isn't leaking now. Go-figure. :/

Thanks though!

Submitted January 01, 2016 at 07:50AM by Lord_Ahrim1536 http://ift.tt/1Specyd