Clip Alpha not showing in the game-engine


I am having some stange problems.
I have an alpha texture which I want to display with clip alpha. The problem is that the texture just appears when the normals are flipped. When they are pointing to the right direction the texture just appears black.

Here are some screenshots for a better illustration:

The alpha texture in Photoshop

The alpha texture with the normals pointing in the wrong direction (in the viewport it is displayed right, but in the game engine they don’t appear at all)

And the alpha texture with the normals pointing right but appearing black (they show also in the game-engine but still black)

Does someone know what could be causing this?
Did I do the alpha texture wrong?

Hope someone can help me out.

Greetings André

Sorry, I found out that it has to do with the light direction… nevermind!