Changing the key of a track

I need to lower the key of a karaoke backing track for an audition on Monday. I've tried this but the key remains the same - anyone know what I'm doing wrong? Thanks heaps: -

Using GarageBand to Transpose a Song Imported from iTunes

First, create a new song in GarageBand
Open GarageBand and create a new song.
Next, drag the song you want to transpose from iTunes into GarageBand
When you drop the song into GarageBand, it will create a track and color it orange. This means that it is an imported song. (In GarageBand a recorded song is purple).
Next, click in the track region to see the audio graph.
Here’s the trick! Press control-option-G and click the track again.
This trick is not documented in the help file for GarageBand, but it is a great tip for changing an imported track from orange to purple, making it available for more editing options.
Now we Edit the Track
Press the Show Editor button (or press Command-E).
The Show Editor button is highlighted in blue above.
Now, click the box for “Follow Tempo & Pitch”
Slide to Your Heart’s Content
There you have it. Your song has been transposed for you. It’s really amazing.
Press Play and Listen to your Transposed Song