I am trying to paint an area about one square foot on the side of my car that I repaired. I had the color computer photoed and mixed twice and have not been able to match or blend to the existing paint. I’ve sanded with 400 grit to get to the base coat and shot the Deltron 2000 base coat and the clear following the directions on the can but still there is a shade or two difference between the old and new. Is there anyting I should try?