Why does my cube look like this??

[Halsafar]

This is the light struct:
m_Light.Diffuse.r = 1.0f;
m_Light.Diffuse.g = 1.0f;
m_Light.Diffuse.b = 1.0f;
m_Light.Diffuse.a = 1.0f;
m_Light.Type = D3DLIGHT_POINT;
m_Light.Position = D3DXVECTOR3( 0.0f, 0.0f, 5.0f );
m_Light.Attenuation0 = 0.0f;
m_Light.Attenuation1 = 0.05f;
m_Light.Attenuation2 = 0.0f;
m_Light.Range = 10.0f;
cGraphicLayer::Graphics()->SetLight( 0, &m_Light );

This is how it looks with a simple 24 vertice cube positions at (0, -2, 10)