Leaking wheel cylinder?

I replaced the power assist unit and the master cylinder in my 66 Barracuda last fall. When I tried to bleed the system, the last wheel cylinder (front drivers side) wouldn't bleed. I replaced the wheel cylinder with a new one and went through the bleeding procedure again. When I got to the replaced cylinder, I noticed braked fluid was leaking. I pulled of the wheel and drum but couldn't see where the leak was coming from. I had someone push on the brake pedal as I watched the cylinder but still couldn't see where the leak was. I pulled the new cylinder and inspected it but couldn't find any obvious flaws.
The only thing I could think of was the place where the hose screwed into the cylinder. The copper washer was present.
I thought I tightened everything down properly so what could the problem be?
Any thoughts or suggestions would be welcomed.