Locking cursor Issue - Flash

Hello.

I have locked cursor but it doesn't work in flash.

 if(Screen.lockCursor)
     gameObject.renderer.material.color = Color.red;
 else
 {
     gameObject.renderer.material.color = Color.blue;
     Screen.lockCursor = true;    
 }

Do u have any idea why it isn't working in flash,but works in unity editor?