Very new and stuck with animating Movie Clip in layer

I’m very new to Flash and after searching for a solution to looping a layer I understand this is best done by creating a new Movie Clip and creating the animation to be looped here.

I’ve done this, and then placed the Movie Clip into a layer on the Scene… but it just won’t play at all. It acts like I’ve placed just the symbol that shows in frame 1 of the Movie Clip and it remains static.

What am I missing?