[away3d] Away 4 transparent texture causes invisible triangles to be drawn

[MADCATX]

Hello, I want to make transparent texture for trees. When I assign
bitmapMaterial.transparent = true invisible triangles are being
drawed:
http://files.myopera.com/MADCATX/albums/6547792/screen.jpg
Screen without transparent textures:
http://files.myopera.com/MADCATX/albums/6547792/screen2.jpg
Models used for trees:
http://files.myopera.com/MADCATX/albums/6547792/models.jpg
So what I should do to use transparent textures without faces, that
should be not visible, being visible?