Can someone help?

I am in Sicily, where I am trying to paint a new metal (iron) stair. I'm having enough trouble figuring out the Italian on the cans of primer and paint, but my top coat is "wrinkling" just after I lay it on. Maybe it's "lifting", "peeling", or getting "fisheyes". It is hard to tell from the various descriptions out of a paint glossary. Tiny mountain ranges, some with cracked tops are appearing in sections, sort of like the metal has poison ivy. Here's what I did:

1. once the stair guys had installed it, I wiped it down with a damp rag, ran sandpaper over it lightly (old sandpaper), and the wiped it with a dry rag. I did not degrease beyond wiping twice, nor added etching primer, or sand very vigorously.

2. Applied a primer that took well and held firm. Let dry for 18 hours.

3. Applied a coat of synthetic enamel gloss (I noticed later that the top coat paint asked for alkyd enamel undercoat). Let dry for 19 hours.

4. Began to apply the top coat of flat enamel, and the wrinkling began within a few minutes.

Help. What did I do wrong, and what next?