screen rotate button not working (elitebook 2730p)

So i have an HP elitebook 2730p as seen in the title but when i try to rotate my screen with the designated (button witch is at the bottom left edge of the screen) but it doesnt do anything. all the other buttons work ( cntrl + alt + del , esc , scroll thing). but when i press the button the wheel next to the mouse shows up for a split second but then dissapears .im running WINDOWS 7