Review on VINYLFROG Changing Adhesive Permanent Sensitive by Amanda Castillo

I bought a set of 6 change sheets in different colours. I used the one that changes color to blue and it didn't change colors. remains transparent. I put this on my cousin's birthday water bottle and it doesn't work. I haven't tried any other colors but I'm very disappointed that this birthday present failed. After that didn't work I checked other reviews and found one that said the one that was supposed to change to blue was defective. I wish I had read this before I started. I have sent an email to the seller, no response so far