I bought this radiator:
P/N 8E0121251AJ cooling system, cooling, radiator & components, radiator 4.2 LITER, MAIN, auto trans
from genuineaudiparts.com

I put it in tonight, fill up with coolant, etc.. start it up, and it starts pissing coolant from the upper passenger side hose connection. It is definitely seated all the way, lock pin thing is in.. just coolant running out still...
Is it as simple as needing a new o-ring? Or is that not the right radiator??

It is a 2005 S4 Avant.