I build mostly short track race cars that body work is not as important than show cars but the problem i have is when i fill area's like panel lines on doors, trunks or 3 piece body seams it takes very little filler.I sand it so it is perfectly smooth, then when i prime it, it seems to show up or almost look as if it has lifted or sunken. What can i do to keep the body work underneath from doing this. I have been using bondo 801 glazing and evercoat glazing putty.Primer is usually plastikote,testors fine gray or tamiya. No matter which combination i use i seem to get the same results??? The panel lines seem to reappear after the next coat of primer or paint. Thanks for any help or suggestions.