Transparent Glass Material not rendering alpha in Blender Internal I've encountered a problem with a transparent material I created to resemble a form of glass. In the scene I have set up, I have a multitude of X "Dummy" Trees propped up in the background to fill the skyline. However, as you can see through the image, the trees that are not behind the POV with the glass look fine while the ones that are behind it act like their alphas are not being used.



Each tree is an 'X' plane with the image of a cycled rendered tree plastered on it. It is made so that only the tree is visible, and the rest of the picture is transparent. 

Is this a problem with the texture made for the trees or the window? Since I also noticed that this same kind of glass created some weird effects on UV textures in another part of this scene. 

EDIT: 
After trying the first suggestion I get this:


It still seems to be prevalent in the trees, albeit some trees, (which I have pointed to), have the problem fixed, while others in the background still have the black rectangles. To the right is my selections for options and shadow.

Here is a copy of the blend file with the stuff needing fixing selected.



Here is the tree files for the Dummy's:
http://imgur.com/a/HTOhC
Your Glass plane uses Raytrace so you need to allocate more depth rays for the amount of transparency changes behind it. I have bumped it up to 6, I guess you'll need more for all those trees?

Alternatively you could switch the transparency type to &quot;Z Trans&quot; but you'll loose some of the nice effects from raytrace.