[Help] Another W2S help thread. :( topic

I'm having some strangeness with my W2S and hoping someone can help..

It behaves as if I'm using the wrong matrix; if you divide the world in half and I look in the direction of 1 side, my w2s works fine; look the other and nothing... w is negative and it thinks objects are behind me..

Here's a quick vid.
[YOUTUBE_ID]1ByKl2nXDPg[/YOUTUBE_ID]

here's my w2s code... is m_ViewProj not the correct matrix to use?

Code:

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bool worldToScreen(D3DXVECTOR3 v3, D3DXVECTOR3* vOut)
{

        unsigned int screenWidth = DxRenderer::GetInstance()->m_pScreen->m_Width;
        unsigned int screenHeight = DxRenderer::GetInstance()->m_pScreen->m_Height;


        D3DXMATRIX viewProjectionMatrix = GameRenderer::GetInstance()->m_pRenderView->m_ViewProj;
        if (!viewProjectionMatrix)
                return false;

        float mX = screenWidth * 0.5f;
        float mY = screenHeight * 0.5f;

        float w =
                viewProjectionMatrix(0, 3) * v3.x +
                viewProjectionMatrix(1, 3) * v3.y +
                viewProjectionMatrix(2, 3) * v3.z +
                viewProjectionMatrix(3, 3);

        if (w < 0.01f)
        {
                vOut->z = w;
                return false;
        }

        float x =
                viewProjectionMatrix(0, 0) * v3.x +
                viewProjectionMatrix(1, 0) * v3.y +
                viewProjectionMatrix(2, 0) * v3.z +
                viewProjectionMatrix(3, 0);

        float y =
                viewProjectionMatrix(0, 1) * v3.x +
                viewProjectionMatrix(1, 1) * v3.y +
                viewProjectionMatrix(2, 1) * v3.z +
                viewProjectionMatrix(3, 1);

        vOut->x = mX + mX * x / w;
        vOut->y = mY - mY * y / w;
        vOut->z = w;

        return true;
}

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