I'm having trouble installing the Spotify Linux preview.

I'm kinda new to Ubuntu so I'm not sure if I did something wrong.

First, in the terminal, I ran this:

sudo gedit /etc/apt/sources.list

At the bottom, I added this:

deb http://repository.spotify.com stable non-free
# deb-src http://repository.spotify.com stable non-free

Then I ran this:

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 4E9CFF4E

Next:

sudo apt-get update

It seemed to have gone well, as there were no error messages.

So next, I ran this:

sudo apt-get install spotify-client-qt

But when I did, I got this:

You might want to run 'apt-get -f install' to correct these:
The following packages have unmet dependencies:
 spotify-client-qt : Depends: spotify-client but it is not going to be installed
E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).

Any ideas?