Visual Depth Buffer!

Hi all! Abstract: I m trying to see what my how depth buffer looks like... when i map it to a ortho plane... it turns out all black... but it does the job calculating shadow map textures... shouldnt i see a gray scale image or do i need some kind of special trick to make it human eye visible? codes: create a GL_DETH_COMPONENT texture ... glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE); glShadeModel(GL_FLAT); glClearDepth(1.0f); glEnable(GL_DEPTH_TEST); glDepthFunc(GL_LEQUAL); glEnable(GL_CULL_FACE); glCullFace(GL_FRONT); GenerateTexture(in_texture); // bind if ID == 0 glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, in_width, in_height); // unset then map it to a plane later on the pipeline... thx