If you have never done the calibration, look for a guide, print the design that represents the autocad menu and with that you can proceed to the calibration.
autocad from what I know does not recognize all the tablets, but may be mistaken, I do not have much knowledge of the subject.
searching on the net anyway I read that recognizes only the tablets equipped with wintab drivers, but more I don't know...
the menu that speaks rpor to print you find it as file inside the directory of autocad. I do not know now in the last two versions if there is still (2009-2010).