unity - Sprite disappears after adding a material to it

I have background which is FirsLayer, order in layer 0 and platform over it which is FirstLayer, order in layer 1.

Once I add a material to the platform, the layer doesn't seem to change but it gets rendered behind the background.

The material that I add:

1)Why do I get such results?

2) How can I add the material to the platform and still keep it above the background?

P.S. For further clarification if somebody didn't understand, I expected the sprite to stay on its original position(i.e. not to go behind the background when a material is being added to it)