I have a mailbox which I wanted to decorate.
Removed all the old paint with sandpaper, degreased it with special enviromental friendly waterbased decreaser painters use and after that with some solvents.
Than i painted the mailbox completely with One Shot enamel, added some One Shot hardener and let it dry.
A few weeks later (today) I thought of making some extra decoration, by cutting a mask of Avery cast vinyl.
When I pulled the vinyl and even the half-tacky masking tape, all the paint came of!
What did I do wrong?

Should I have primed it first? What kind of primer?
I thought One Shot enamel was the best paint to adhere on metal (this was galvanised steel by the way).

