I need help with D3D normals!

[/\/\isanThr0p]

My problem is:

I want to have a plane(trianglestrip) that is visible from below! I use the DrawPrimitives method.

How do I have to set the normals?
I tried some (I think all) combinations of normals and it was alway only visible form above!
Do I have to set special values at the drawprimitevs or can't I use a vertexbuffer?

Thank you in advance.

[parksie]

Flip the up/down normal. For example, if you are using y as up, then set the normal to <x,-y,z>