Banjo fitting won't seal

Not a-body put new calipers and hoses on motor home banjo fittings won't seal at caliper are the copper washers a one time use? Surfaces look flat on both hose and caliper tried two warshers no difference Chevy P 30 chassis
Thanks for any help
I used to reuse the washers on my p30. Take them off the nut and spray everything with brake clean. The smallest piece of dirt or sand will cause a leak.