Thats weird, tell us more about what kind of Primer are u using
and the area your spraying primer to is that the original basecoat , are you using spray cans?
i'm a noob myself but i remember somebody saying some primer dont mix with some other chemicals ummm something like acylic and enamel something like that.
anyways im sure if u answer any of my questions it will help u get a better answer
btw by best bet by just reading your post i would go with Dirty dusty area
did u tach?