CL - We are sorry to hear you are having trouble getting the product to work. Please call out toll-free support line at 888-842-3356 and we will gladly help you troubleshoot your problem.
Please note, the surface must be clean and dry AND free of any soap residue before the InvisaTread solution is applied. You mentioned "cleaning the tiles twice", many soaps leave a slippery residue. It is possible a film of soap residue is interfering with the application process. Try using TractionWash or another high alkaline, free rinsing, cleaner/degreaser. Rinse and dry the surface and feel for any soap residue. Using a wet vac or other extraction device helps mitigate these issues; as well as speeds up the entire process.
Some tiles just require multiple applications depending on the density, bisque, glaze, level of dirt, etc.
Good luck and please do to call us for assistance!