Creating a plane in screen space coordinates?

I'm trying to define a plane in screen space coordinates but for some reason am not getting anything on screen.

My definition:

// Vertex layout semantics are { SV_POSITION, COLOR}

Vertex v[4] =

{

{DirectX::XMFLOAT3(-1.0f, -1.0f, -1.0f), DirectX::XMFLOAT4(1.0f, 0.0f, 0.0f, 1.0f)},

{DirectX::XMFLOAT3(-1.0f, 1.0f, -1.0f), DirectX::XMFLOAT4(0.0f, 1.0f, 0.0f, 1.0f)},

{DirectX::XMFLOAT3( 1.0f, 1.0f, -1.0f), DirectX::XMFLOAT4(0.0f, 0.0f, 1.0f, 1.0f)},

{DirectX::XMFLOAT3( 1.0f, -1.0f, -1.0f), DirectX::XMFLOAT4(1.0f, 0.0f, 0.0f, 1.0f)}

};

I thought I have to define the plane in NDC without any need for the usual View and Projection matrices, and the vertex shader would just be a pass through without modifying the vertices, but for some reason the plane is not showing up on screen. Am I setting it up wrong or is the issue elsewhere?

Thanks.