OnMouseOver how does it work?

Hi im trying to make it so when i right click a cube it loads the game scene but i cant get it to work can you guys help me out? ive also tried onmousedown but not matter where i click it loads the scene

function OnMouseOver()
{
   if(Input.GetMouseButtonDown(1))
   {
       Application.LoadLevel ("GameScene"); 
   }
}

OnMouseOver will happen anytime the mouse goes over a collider and it will call the onmouseover on that collider. If you want it to be a click do OnMouseDown for a right click you will need to test what click happened so use Input.GetMouseButtonDown(1) inside the onmouseDown function or even on onmouseover