Locked out of track – Help, please!

I recorded a Skype interview for my podcast. The audio file was saved to my Macbook as a .mov file. It opens and plays beautifully in Quicktime.

However, when I import it to Garageband (10.1.2), the track is locked. I've tried everything to unlock it but to no avail:

1. Click on the Lock icon and nothing happens

2. Keyboard shortcuts involving the letter L don't work either

This has never happened before and I'm at a complete loss.

Can anyone help?