I'm using a 3D game engine, that uses a 4x4 matrix to modify the camera projection, in this format:

 r r r  x
 r r r  y
 r r r  z
 - - -  zoom

Strangely though, the camera does not respond to the Z translation parameter, and so you're forced to use X, Y, Zoom to move the camera around. Technically this is plausible for isometric-style games such as Age Of Empires III. But this is a 3D engine, and so why would they have designed the camera to ignore Z and respond only to zoom? Am I missing something here? I've tried every method of setting the camera and it really seems to ignore Z.

So currently I have to resort to moving the main object in the scene graph instead of moving the camera in relation to the objects.

My question: Do you have any idea why the engine would use such a scheme? Is it common? Why? Or does it seem like I'm missing something and the SetProjection(Matrix) function is broken and somehow ignores the Z translation in the matrix? (unlikely, but possible) Anyhow, what are the workarounds? Is moving objects around the only way?

Edit: I'm sorry I cannot reveal much about the engine because we're in a binding contract. It's a locally developed engine (Australia) written in managed C# used for data visualizations.

Edit: The default mode of the engine is orthographic, although I've switched it into perspective mode. Its probably more effective to use X, Y, Zoom in orthographic mode, but I need to use perspective mode to render everyday objects as well.