Tutorial 4 does not render any content


Hi guys.

I have 2 PCs
1 ) Windows 7 machine with a NVidia Device
2 ) Winodws 8 with an ATI Device

On the Windows 7 machine everything is working fine.
On the Windows 8 PC the Tutorial 4 does not render any Content. All I get is an empty Window filled with the color I set to clear the RenderTargetView. But Tutorial 5 (the one introducing Textures) is working fine on both machines.