Brake fluid leak!

So I put 94+ cobra brakes on 1990 GT, and for some reason I can get one of the hoses to seal, its the hose that goes from the center of the rearend to the chassis of the car, its leaking were the soft line meets the hardline of the chassis I put new copper washers on it and it still leaks the banjo bolt is good, the softline is good, and the hardline is good. What could be the problem? it didnt leak before, and Im pretty shure its the first time that line has been unconnected if that makes any difference, anybody know what the problem is? thanks.

So as of today the leak is gone for now, went to the junk yard and got some good used copper washers(all the ones I got at the parts store were bunk) and tightened the crap out of the banjo and it stopped leaking.