Set new zone inside current zone?

Hello! I am trying to set a safe zone for my players with pvp off. However, I want to set another zone inside this zone to be used as a duel arena.

When I attempt this by setting the large zone around the area, naming and etc, and try setting another zone inside this zone it seems to remove the large zone? When I check, the large zone doesn't seem to exist. Any help?

i figured it out...