Leaky drain, round 2: Trap joint won't stop leaking
I'd say take it all out and start over. Avoid RTV and flexible fittings. Put a standard tailpiece onto the sink, a starndard trap like brhans mentioned, and a slip nut on the pipe going into the wall. Then it will easier to take apart and clean. Or take apart in case you drop something value able down there. Google image search "standard p trap setup". Or just look under somebodies sink.