Materials Assigning problem

Hi! I’m very new in blender,I found a sample model on the net and try to export that in unity.The model uses cycles render.When I’m in the rendered viewport,I can see all textures i cluding materials,but when I switch to Texture Viewport,I can see only textures assigned but the materials are not applied,the artist used Mix shader surface and the materials are listed in materials tab,It’s just when I reassign a particular material,nothing happens,I tried to change the Surface from Mix Shader to Diffuse and chose color red and reassign to selected faces but noting happens,please help me.Thank you in advance and more power