Ensure that you have installed the latest version of Personify Live from the website.
Check that you have one of the supported cameras (http://support.personifyinc.com/knowledgebase/articles/136936-what-kind-of-camera-do-i-need-to-use-personify-liv)
Tips for the Windows installer:
Tip #0: The Personify Live installer will install all the drivers and dependencies you need. Avoid installing any drivers yourself so there are no conflicts. If you installed the Kinect for Windows drivers and you're using a Kinect for XBox camera, then uninstall the Kinect for Windows drivers.
Tip #1: If you're using the Asus Xtion Pro Live or Primesense ensure that you click 'OK' on the driver popup (from Primesense) during installation
Tip #2: Check that your Kinect/Asus camera is connected to the USB port and powered up. Try different USB ports on the same laptop (occasionally, some of them are not high powered enough to support the cameras)
Tip #3: To uninstall and reinstall, simply go to Add/Remove programs and uninstall the drivers from publisher 'Primesense'. Reinstall through the Personify Live installer keeping in mind the tips above.