Vampire Teeth mold alternative mixture question?

Ok, so i bought my step daughter a set of Vampire teeth, and the instructions say to open a capsule that it comes with, and mix it with a 5 drops of a liquid that it also comes with, HOWEVER, the liquid was not a liquid (seemed like a jelly, but we couldn't get it out of the bottle, much less mix it) so i tried to take it back, but the place we got it at is being...less then cooperative. I am gonna do something about that later, but my question is what can i use in these teeth before Holloween to get them to stay on her teeth?