Check if Kinect.SkeletonStreams.AppChoosesSkeletons is TRUE or FALSE. I had the same issue, and I set it to true earlier but somehow it is false, and that's when I receive the error. Also, if you catch the exception and then output the exception.ToString() you get a lot of information on the error.
Now to find out why it is becoming false. I know the first post is a little old but hopefully this response helps someone along the way.