Try a second coat of the decal potion. I've recently had the same issues, and it seems that a thin coat of the stuff sometimes doesn't work.
I also found that it helps to put a little additional application of the liquid all around the outside of the image area. That's where my decals were flecking off pieces.
Finally, cut around the decal with a knife rather than scissors. That seemed to work best for me at least.
Good luck with it. It's frustrating to have a decal sheet go bad like this.