by DredNicolson » Fri Apr 28, 2017 10:55 pm
For Internal, enable Transparency for the material, set the default alpha to 0 (fully transparent), go to the diffuse texture channel and check on Diffuse Color and Alpha under Influence, so the material gets both color and alpha information from the texture.
Also check the Render Layers tab and make sure you haven't accidentally disabled ZTransp (if that's the transparency option you're using).