I'm following a book on character creation in Blender and I'm currently trying to composite my character within real footage through camera tracking. I'm at a part where I'm trying to set up the character and its shadows in a separate Render Layer and adjust them through Nodes. However, in the book, the two Render Layers have a transparent image showing. They're not showing for me. Also, adjusting things like the RGB curves has no effect. Have I set this up right? Or have I missed something?