The Dreaded Tranny Pan Leak

SBM 727, Hughes 3000 stall, steel stamped plus 2 quart pan.
This will be the thrid pan gasket I have tried, I cant keep it from seeping between the pan and the gasket. First gasket was cork, second gasket is stiff rubber like with ridges in it, still leaks. All gaskets were installed clean and dry, no sealant used.
What trick am I missing here? Sealant?
See my new thread
" I fixed the dreaded tranny pan leak"