Rotate MC by 90 left or right

Hi,

I need to rotate the movie clip (instance name: “mover”) 90 degrees left or 90 degrees right when the corresponding button is pressed. I can get this to work for the first button click only. And I need to keep incrementing 90 degrees with every button click’

Ive attached a file that will make what im talking about more obvious (I hope :wink:

Thanks