Can't add a material to a layer

[Anonymous]

If i choose a generic wall, and spilt it into layers, and let say the middle layer is going to be insulation, when i click on the material button nothing happens?, I can't load a material, it's a huge problem, and i have tried to repair revit, and uninstall in then reinstall, didn't work.

And now im running out of ideas, i'm a student and need to use the program, hoping for your help!

[Anonymous]

Duplicate the Generic Wall, rename it, then go into Edit Structure and add "layers" for various compound materials.

Then click on Material while in Edit Structure. 

[Anonymous]

I have tried the method you described, but when i want to define what the layers consist of, nothing happens when i click on the material button!