with help i have created a very simple skybox. In the skybox i have a model of a ship, when the ship moves the skybox moves. This is the code that deals with this:
if (keystate.IsKeyDown(Keys.W) == true)
            vecSpherePositionOff += 0.0003f;

        //find out what direction we should be thrusting, using rotation
        addmuch.X = -(float)Math.Sin(modelRotation.X);
        addmuch.Z = -(float)Math.Cos(modelRotation.Z);
        addmuch.Z += vecSpherePositionOff;
        addmuch.X += vecSpherePositionOff;

        vecSpherePosition = cameraPosition;

        vecSpherePosition += addmuch;
        //Update sky sphere
        m_skySphere.SetCamPosViewProj(vecSpherePosition, m_mtxCamView, m_mtxCamProjection);

When when i compile this code i get no errors but when i try and move the skybox nothing happens!!! Any ideas

P.S addmuch is an empty vector 3