This means that the camera's driver isn't installed properly. Firstly, install the camera driver and reboot the computer. You can find the driver on the support CD that was delivered with your product. Reboot the computer and it should work normally. However, I recommend on using another product instead of Dell Webcam Central. Dell Webcam Central isn't very "flexible" when it comes to handling the camera's stream. Try the YouCam application from the official website instead of Dell Webcam Central.
