Why not transparent a back side material?

Support Materials and Textures
1

I made a material node.
But, it’s have problem.

Why not transparent a back side material?

See below image :

Why not transparent.jpg683×561 87.3 KB


Why not transparent 2.jpg635×623 68.8 KB

And Here is modeling Source file :

http://imall.da.to/tmp/Transparency.blend

http://imall.da.to/tmp/Transparency2.blend

Please answer to me.
Thank you.

2

Why are you ignoring alpha components of materials in Node editor?

http://www.pasteall.org/blend/30628