Can't open magnet link on Ubuntu-Gnome 16.04

I'm running Firefox on Ubuntu-Gnome 16.04 and when click on magnet link get: The address wasn’t understood Firefox doesn’t know how to open this address, because one of the following protocols (magnet) isn’t associated with any program or is not allowed in this context. I've tried all kind workarounds and nothing helps. In this images are my current settings that should work but they don't. https://i.stack.imgur.com/aaCiZ.png https://i.stack.imgur.com/ck4O4.png $ whereis transmission transmission: /usr/share/transmission $ whereis transmission-gtk transmission-gtk: /usr/bin/transmission-gtk /usr/share/man/man1/transmission-gtk.1.gz $ ls /usr/bin | grep transmission transmission-gtk $ ls /usr/share | grep transmission transmission