no depth values in FBO

hi, i’ve started to integrate shadowmapping in my 3d engine. The engine uses almost fixed function with the ability to use shader.

After setting up my depth FBO everything seems to be fine. The depth values are correct. at least for normal objects. If i try to render Alpha masked shadows then they don’t whole mesh doesn’t write anything in the depthbuffer.

the depthbuffer FBO is set up like the one from ATIs SDK.
If the textures are masked I use:


and on initiation I define the glalphafunc to be GL_LEQUAL,0.5

well, the textures are diplayed correctly but the mesh is not displayed in the depthbuffer. If i disable GL_ALPHA_TEST the whole match is shown in depth, but eg trees or grass needs masked textures.

Any ideas?