How to go about using alphas?

[JonnyAnomaly]

Hi,

I'm making some trees in Maya at the moment but I'm stumped with how to use alphas for branches and things in the engine. I understand how to use alpha channels in Photoshop and use them on planes in Maya to create the branches, but when I had finished I realised I was using two textures - One for the bark, and a targa for the branches. I loaded up the pine.dds from the actual game and saw that they used the alpha in the bark texture, but when I do that and save as a .dds, the alpha doesn't work in Maya and is just black.

Can anyone help clear this up for me please?