To get the patch(tablet) to stick, it's important to DRY THE SORE, then press the tablet in place for at least 15 seconds. For the first 5-10 minutes, be careful not to dislodge it, especially when swallowing. If it falls off, the wet tablet won't stick again.
It's hard to get the tablets to stick to sores on the tongue. Get the sore REALLY dry before applying the tablet, then tip your head back and stick your tongue out for a couple of minutes. Sounds crazy, but it immobilizes the tongue and helps you not swallow, which gives the tablet a chance to really stick.