We wanted to repaint son's bedroom where he had some ink writing and mars on his walls. We got Kilz oil base primer and applied one coat. We then tried to paint over this with a Glidden latex paint we had previously purchased. Now we can't get rid of the lighter stains from the Kilz showing through. WE have tried several coats and also to put another coat of latex Kilz on, but it still doesn't look uniform. White showing through. Any suggestions?