Shaders overlay problem

I'm having a little problem with a shader, I not yet have much knowledge in unity and solve this is becoming complicated.



The little white circles is a .png (with transparent BG) behind the big grey circle(just a grey sprite renderer Z= 0) with this settings (white circles settings).



The problem is the white circles should not appears when behind the grey circle.
Really appreciate your attention.

 

I don't know why but i solved the problem while pulled away the camera to another config.