fuses are good ......no license plate lights either......

so i took the bulbs that i know r good ( blinker) n set it on my ground on the batter n took my test from from the positive and touched it to my buld and my tester lights up on any good bulb i do it to .......when i do it to my break light bulb and my license plate bulbs it does NOT light up......soooooo im hoping that by some freak thing all four bulbs are bad n if i run to the parts store n replace them then maybe ill b ok.......but im not optimistic , how all 4 b bad at the same time?

I also did bypass the brakelight switch and i DO have power back at the tail light plug in a terminal that i did not have power at b4...........