Unity 2D - Material for light

Hi there , i have a problem.I am creating a 2D game and i want to implement light.I created diffuse material,but when i put in any sprite that has alpha channel it will create some weird stuff.

96136-light-material.png

SOLUTION

I am so sorry.I had selected bad shader…
You need to select Sprites/Diffuse

have you triedself-illumin/diffuse