Trouble with World-to-screen point on Oculus 0.4.3.1

Hi

I am trying to use make it so that I have a marker on the GUI which shows me the location and distance of another object relative to me. I have managed to get this working with a normal camera.

When I try and use this with the Oculus Camera however, the y-values are completely off. If I get further from the object, the marker's y-coordinate increases rather than staying the same relative area.

Here is the GUI code:

Vector3 itemToScreenPosition;
float distanceToTarget;

void Update()
{
     itemToScreenPosition = rightCamera.WorldToScreenPoint(targetTransform.position);
     distanceToTarget = Vector3.Distance(targetTransform.position, rightCamera.transform.position);
}

void OnVRGUI()
{
    textureDimension = new Vector2(Screen.width / 10, Screen.height / 10);
    float posX = itemToScreenPosition.x;
    float posY = Screen.height - itemToScreenPosition.y;
    GUI.DrawTexture(new Rect(posX, posY, 
                textureDim.x, textureDim.y),
                locatorTexture);
}

I'm using Unity 4.5.5p3 and Oculus SDK 0.4.3.1
I am also using the VRGUI package which basically just converts normal unity GUIs into an Oculus GUI mesh. It's been working for me so far, except for now.

Thanks