Error: Exceeded Maximum Number of Server Script Variables

Hi. I just bought an Xbox 360 Kinect. I started playing Call of Duty: Black Ops and I keep getting an error message when playng the campaign Vorkuta. The message reads: Error - exceeding maximum number of script variables. The screen is black except for the error message and there is the green 'A' icon to enter. When I press 'A' it takes me back to the start screen. When playing this level, I have to constantly fire at the 3 targets but nothing happens. Then after many shots the error message appears.

I need help, i dont know how to move on. --If there is anything you know to fix, please help--
Thanks,