After I hooked everything up and made sure everything was tight, I turned the water on to see for any leaks. Everything drains, but I have a small leak under the compression nut that tightens the p trap to the 90 deg elbow that goes into the pipe in the wall. Basically, it drains some water that is left in the trap. Not a big leak, but a leak none the less. My question is, am I missing anything on the hookup? The only thing I can think of is there is a plastic piece that goes of the lip on the 90 deg elbow where it goes into the p trap. Other than that, I am out of ideas. Help?