I recently installed a new front crossover stainless steel brake line on my 77 vette, but I am having leak issues where the flare fitting meets the proportioning valve. I purchased a custom brake line with the tube ends already flared so the parts should be compatible.  Any ideas on how to prevent this leak? When the brake pedal is depressed, fluid can be seen rising out of the fitting connection. It appears that the flare is not sitting properly but I've tried countless times and still cannot get it.  Any suggestions?