Port forwarding doesn't works

Hi, i've bought the Netgear d7000 Nighthawk but when i try to configure the port forwarding it doesn't works. In lan if I visit the link/address 192.168.1.251:81 on a browser the server response with the webpage but if I try to access from publicip:81 it doesn't works.

This is my configuration: http://i.imgur.com/bdnooxz.jpg

I have the same problem using port 80. Only DMZ works.