The ability 'No Guard' allows you to always hit - provided type immunities aren't in place. Unfortunately, No Guard doesn't ignore Doublade's ghost typing meaning that Normal and Fighting attacks still don't do any damage at all - so that's why it didn't affect it.
The only ability which allows Normal and Fighting moves to hit Ghost types is the ability 'Scrappy', or the use of moves like Foresight allows you to have that same effect.