Thanks for the response. The flex lines that I purchased at the hardware store have no issues. Where the leak is is where I connected the 1/2" adapter to the ikea faucet flex line that came with it. They are different and have only a rubber washer which does not work. If you just used stock washer with faucet, then I have done something wrong. Again,much appreciated.
I have the exact same problem that you have David - the 1/2" female connection on the supply hose for the cold water part of the faucet has a black rubber o-ring that is supposed to seal against a male brass fitting. It does not seal the connection. I tried leaving it somewhat loose, then tightening it and testing it several times, still with no seal. After it failed as tight as I could get it, I took it apart and the rubber o-ring was torn apart. I tried it again with a fresh o-ring with the same results at increasing levels of tightness. Any idea on how to get this to seal? How did you get it to work?