Keyboard Shortcut to launch a Terminal

I just installed Ubuntu 15.10 and I'd like to set a keyboard shortcut to launch a new terminal. I opened the Keyboard Shortcuts and set the shortcut for "Launch terminal" to Alt+N. But, when I hit ALT+N, nothing happens.

I also tried a custom shortcut. The name of the short cut is "Launch New Terminal". The command is gnome-terminal. I set the shortcut to ALT+T. But, when I type ALT+T, nothing happens.

What am I doing wrong here? How can I debug this? Are error messages being logged anywhere?