Unable to drag layers for lipsyncing

I am following a tutorial for using Papagayo to lip sync. According to the tutorial, you have to drag the .pgo file into the group, then drag the mouth files into the .pgo mouth files.

My problem is no matter what I try, the files refuse to connect. It drags, but doesn’t group.

What is the problem?

Which tutorial are you using? I got it to work, but it’s kinda buggy.