Did you put it on while the skin was wet? That can make it not stick. So can applying it after you've put on lotion. Skin is meant to be clean and dry when you put it on (ie nothing that could possibly interfere with the stickiness). Also, putting lotion on after you've applied the patch, you need to take care that you don't get the lotion close to the patch, as that can interfere, too. If your patch isn't sticky any more, get a new one and put it on to insure you're protected. If it's not sticking, chances are the hormones aren't getting into your system.
You can go to your pharmacy and ask to buy one replacement patch. They should give it to you, as they should be quite used to situations like these.