How to get Alpha to show on Tree Leaf Billboards?

[Mr Maison]

I made a weeping willow. The PNG texture map have the leaf/branch cluster with transparent background and the bark taking up the other half. In the game/editor, the transparency does not show up.What did I miss?

 

[Mr Maison]

I figured it out after some trial and error and reading the wiki. I made a greyscale image with a white color overlay on the leaf layer as well as the bark against a black layer underneath and made an alpha texture with _a at the end and it worked.