This why the pro painters do a color card..your paint supplier should have some of those..shoot a sample on the color card and roll the vehicle outside and hold the color card up to the car to see if the match is good. if not all you are out is a can of paint..
Everyone in the auto repair business gets bit on occasion with something so you are not the only one this has ever happened to..
Only solution I know is to paint the rest of the car
Sorry for your issue..
I have tried most all of it and now do what is known to work..