Clings for our Mustang Club

I'm very happy with the speed of service. Had my clings in a matter of days. The colors were exactly what I had ordered. The only problem, when trying to cling to and inside glass, they did not hold up. Even when I peeled the backing off I experienced the same thing. I talked to a representative and he assured me they cling on from the front and back. The only way I got to cling to glass was by wetting them slightly with water and that did the trick. Not sure if that is recommended or not.