Created Material Shows Dark Sprite

For testing purpose I have created texture material using following way :

Assets → Create → Material.

Then I assign a sprite to it. My created material look like following image.[22021-screenshot+2014-02-11+17.49.44.png|22021]

So my question it how to make this sprite brighter in its normal situation. I didn’t perform anything else.

I have changed my shader setting of material to tk2d/BlendVertexColor and I get normal sprite in display.