Ubuntu :: Cannot Add/edit Shortcuts ?

I'm a xubuntu 10.04 user and i recently tried to create a keyboard shortcut to launch the Terminal. I went into Settings -> Xfce Settings Manager -> keyboard

I chose the "application shortcut" tab and there I realized that the "add" function behaves very strangely.

A window pops upp with a text entry that lets me add a command name, but nothing to enter the shortcut's name. Anyhow, whatever I write in there, the window closes when I enter OK and nothing more happens.

I also tried to change the shortcuts from the Window Manager and nothing can be edited there either.