Well, if the paper label/product information all say "Ultracote"....The product is more generally know by the rest of the world as "Oracover". I think originally made in Germany. But likely not any more. My guess is you have rolls of wildly varying ages. Some of my oldest stock, going on 30 years, isn't as "sticky" as newer anymore. You may want to look for a brush on heat sealing helper, like "Stick-It" that you coat the surface with first, let dry, and then put the Ultracote down on. Essentially extra heat activated glue....More importantly, do all the rolls color match? While there can be slight differences between production runs, Ultracote is pretty standardized. So if the color variation is pretty noticeable, you may have gotten a substitute....