Because the activation servers for 2009 have been retired:
Released in March 2008, AutoCAD 2009 introduced a major user interface redesign, including a Ribbon, the Action Recorder, and improved 3D navigation via ViewCube and SteeringWheels. This update aimed to enhance drafting efficiency with features like modeless layer management and Quick Properties. A detailed overview of these features is available at AUGI Forums autocad2009 updated
While 2D drafting remained a core focus, 2009 pushed 3D capabilities further: SteeringWheels and ShowMotion Because the activation servers for 2009 have been
Go to "Turn Windows features on or off" in your Control Panel. Run as Administrator: including a Ribbon