Depth Buffer woes.

I’ve got a problem and I can’t seem to find a solution to it. It seems as though the depth buffer in my program is permanently disabled. I’ve tried everything I can think of to fix the problem, but nothing has worked.

I know that Depth Testing is enabled because I did a check in my main rendering function before I do anything. I also know that the test is Less than or equal (done in same check). But the depth buffer is still not working.

This is what I how I set up the depth buffer:
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);

This is driving me up the wall!