My pen tip does not work. The eraser part works but the tip does not work. I have changed the tip but no luck. Does anyone have any suggestions as to what it could possibly be? I have noticed that the scroll wheel light fades in and out. Is this normal? When I use the eraser part of the pen the colour stays solid, but when I put the tip down, it fades in and out of colour. Also when there is nothing on it, it seems to be fading in and out. Could this be the problem that I am having with my pen tip? Thanks for any help.