Even though your system is equipped with position sensors, the Locate Me button on the Geolocation Ribbon tab may be unavailable for several reasons.
If you are using Windows 7, AutoCAD cannot communicate with the location sensor unless you enable them in the Windows' control panel.
If you are using Windows 8, AutoCAD cannot communicate with location services unless the "Let apps use my location" setting in privacy settings is turned on.
If you are using Windows 8, AutoCAD cannot communicate with location services unless the administrator setting "Windows location platform" is turned on.