I have a problem with the gluPickMatrix. My program draws a 3D -mesh. I want to select the elements of the mesh with the mouse. Im using gluPickMatrix and glFrustum and I set the RenderMode to GL_SELECT, the DepthTest is enabled. Everything is working fine at a lot of computers. But on some computers the program dosen''t select the element which is in front of all. It selects the element which has been drawn at last. The SelectBuffer contains the numbers of the elements, but not the values for the depth. These fields are all zero. Please help me, even if you are not sure. Thanks