I agree, You should use a Fernco rubber boot. This is a rubber coupling. Here's a link that shows one:
http://www.brandnametools.biz/plumbi...ipe_Couplings/
One end slips over the drain piping stubbed out of your wall. In the other end you'll have to install a threaded male pipe nipple They're also called a street fitting but the picture on this link will give you an idea of what you need.
http://plumbing.aubuchonhardware.com...ack-432696.asp
They're only about 2 inches long. Install it about 1 inch into the Fernco boot, tighten down the clamp. Then the threads that stick out from the boot are where you attach your PVC. Apply teflon tape to the threads and use a metal nut around the PVC.
This will give you a much better seal and also be sturdy.