Airplay Dual Display

I used the script on the manual

void Start()
{
// GUI is rendered with last camera.
// As we want it to end up in the main screen, make sure main camera is the last one drawn.
extCam.depth = camera.depth - 1;

camera.SetTargetBuffers(Display.main.colorBuffer, Display.main.depthBuffer);
extCam.enabled = false;
}

void Update()
{
if(Display.displays.Length > 1 && !extCam.enabled)
{
Display.displays[1].SetRenderingResolution(256,256);
extCam.SetTargetBuffers(Display.displays[1].colorBuffer, Display.displays[1].depthBuffer);
}
extCam.enabled = Display.displays.Length > 1;
}
​

When a start the app , my mirroring mode gone black.... i think i started well the display but i can't send my camera render somebody can help me????

 

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