title: Unable to adjust Brightness in Hp probook 4430s
body: <p>I recently installed Windows 7 professional for my laptop and I am unable to adjust its brightness when I using fn+brightness(low or high) button , I see the symbol but it does not change.</p>
  
  <p>I have tried other methods but they have not seem to work for me.</p>
  
  <p><a href="https://i.stack.imgur.com/zRMZM.png" rel="nofollow"><img src="https://i.stack.imgur.com/zRMZM.png" alt="Below Image shows when I pressed the fn+ brightness(high) button symbol came but brightness did not change on repetitive press for brightness while holding the fn keys."></a></p>
  
  <p>Thanks,
  Akshay</p>