Putting down a commercial grade peel and stick vinyl floor on 60 year old concrete. It had the old black adhesive and 9x9 floor tile. The tile is removed, but there are traces of black adhesive. Cleaned, vacuumed and mopped. Let dry. Putting tile glue down until tacky before laying vinyl tile. My problem the tile is curling at the corners. What is the problem? Do you have any suggestions? Thank you MaryEllen