Why can't anyone other than me connect to my server?

I'm using the bukkit server along with the no-ip set up, which basically changes the ip address from a bunch of numbers to a name. When I try to connect from any device connected to my router, everything is fine. However, when I use port-forwarding checking websites (ex. canyouseeme.org) it says that it cannot reach port, and I'm pretty sure that this is the main problem. I heard something about how I need to give others my external ip address, but that doesn't work, because I'm only forwarding the port of my internal ip address. I'm not sure if this makes a lot of sense, but could you please help me solve this problem? Thanks in advance

<Removed double post - Use edit button to edit your post - Necrodoom>

 

Make sure that it is forworded to the to the right computer and that the server is on. You would also would want to check if your computer's firewall is allowing Java through it to Public networks.

 

I'm not sure what you mean by forwarded to the right computer, but the server is almost always on and my firewall is disabled