Using a Z-Buffer in Windowed Mode [Resolved]

Does anyone know how to use a ZBuffer in Windowed mode? I can use one in Full screen but if I run it in Windowed mode I get an error when the following line is called:

VB Code:

D3DDevice.Clear 0, ByVal 0, D3DCLEAR_TARGET Or D3DCLEAR_ZBUFFER, BColor, 1#, 0

So I removed the "Or D3DCLEAR_ZBUFFER" and now nothing apears(well apart from a blank area the color of BColor). However if I remove the line that enables the ZBuffer:

VB Code:

D3DDevice.SetRenderState D3DRS_ZENABLE, 1

Then now it works but you can see both sides(Basicaly theres no ZBuffer anymore).

Is there someting I'm missing? Thanx for any help.

I fixed it, I missed out this line:

VB Code:

D3DWindow.EnableAutoDepthStencil = True

For some reason it didn't make a difference in FullScreen.
Oh well, works now anyway.