tut not happening

I have been following along the basic traditional animation tut - https://www.toonboom.com/resources/video-tutorials/video/basic-traditional-animation
but what she is saying is meant to happen is not happening for me.

When I click on the show key drawings button then press play it is not flipping through the keys only. Also I have enable onion skins on but I can see no onion skins.