We have seen some boards where the Rref (5k6) was not of the specified accuracy and did give wrong temperature results.
But anyway attached a working example for Keil MDK - just checked again on a ADuC7061 MiniKit.
Have seen the effect from the wrong Rref - see extra line of code where I did correct the value.
If you use a ADuC7060 Evaluation-Board you may check the DIP switches as explained in the UG-029 and also the Rref.
http://www.analog.com/static/imported-files/user_guides/UG-029.pdf