Glossy Spray Paint

I am painting arm chair with wood spray paint Krylon gloss black. I put on several layers, but the finish is a bit dull and scratched. What happens? And how can I solve this problem?

try sanding with about 320 grit sandpaper. The bubble is your problem, it will open the bubbles and you can fill them with another layer of paint.

lightly sand with 320 grit sandpaper and give it a coat of varnish should do