OK so where is the OP so that we can determine, without a doubt what kind of primer he is referring to. . .it DOES make a huge difference.
If lacquer, strip it
If epoxy that has cured longer than the tech sheet allows for recoat then scuff with a scotchbrite.
Betcha 2 oz of pearl additive the primer was lacquer! But I have been wrong, in fact, several times today alone haha!
Check the progress on the second re-incarnation of the same '70 sport coupe (in 6 years)at: Click Here