cv::Tracker class not shown

edit

I'm just download latest OpenCV library (version 3.1). Write all external dependecies in solution properties (C/C++->General, Linker->General and Linker->Input->opencv_world310d.lib). So make includes in project file:

#include <opencv2\core.hpp>
#include <opencv2\highgui.hpp>
#include <opencv2\imgproc.hpp>
#include <opencv2\video.hpp>
#include <opencv2\videoio.hpp>
#include <opencv2\video\tracking.hpp>
#include <opencv2\video\tracking_c.h>

And when i want to use example from opencv gihub, it make red the line cv::Tracker class, cannot find this class. Can anybody help?