Transparent Things? HELP!
 

I am part of a modding team, and a fellow member has run into technical difficulties. On one model, we are trying to make the windshield transparent. So this team member decided to make the alpha-channel for the windshield black. Instead of the thing looking like glass it looks like something invisible! You can see right through it! No tint at all. And he also tried to make the channel a little bit lighter, kind of dark gray, and instead of it looking normal it became white like an untextured model.

What's the problem here? Can anyone help?