Painting galvenised up & over garage door

Have just removed all peeling paint from good condition galvanised door. I think the mistake I made was painting it last year using a car spray grey primer. This doesn't appear to have stuck to the galvanised (exterior) surface. There is no rust - can someone please advise on suitable primer (if needed) I don't want to do it all again next year.

 

Thanks Sean for that - Zinsser is confirmed by another member. Yes, I've not had results I'd have expected from Hammerite.
Sorry for the delay in replying - been mending fences.

 

Thanks for the recommendation - will be using that as soon as I can get started

 

Thanks to Sean-ork and yourself for the replies - have now got a tin - did'nt realise that it was available at such reasonable cost at my local Screwfix store. Surprised that there are no prep. instructions on the tin, other than the usual stir required. I use sugar-soap on timber - would that be o.k. on galvanised metal - or should I brush it straight onto the scraped off surface. Thanks in advance, when it stops raining I'll get started.
Mike 223