We have spend all morning installing a new faucet and pop up drain in our bathroom. Everything works fine except the drain is leaking right underneath at the black gasket. We have done everything according to the instructions and put putty underneath the part the is visible from the top. We put the gasket as tight as possible to the sink and it keeps leaking water right there. This is supposed to be a simple thing. I am not sure if I should use putty on the bottom as well. Also I am trying to figure out why the drain has holes in the metall piece. Obviously, water is going to get behind there. I am also thinking that is the water that is now leaking. Any suggestions would be greatly appreciated.