Why can't I portforward an Minecraft Server?

I have followed the tutorial appropriate to my router (Netcomm) on portforward.com and have tried to open up the port 25565, the default minecraft port. I use my external ip address and add:25565 yet I can't connect to my up and running server on version 1.7.2. No one else can join it, and when I used PFPortChecker, it said neither TCP or UDP could find 25565. Any help?

Make sure that you have gone into the minecraft server file and had it using that same port.