Don't use slashes "/" as part of the shader name. It will disconnect it from the tree. I didn't understand why I couldn't connect a certain shader until I realised it was in the name. I guess the code looks at the actual name of the shader instead of a numerical interal ID (or something similar), which (being a coder myself) I would have done. The name should be nothing more than a property, not it's defining element (code wise that is).