openCV SURF error

我使用的是opencv 2.44, visual studio c++ 2010当我编译时，我得到这个错误

错误1错误LNK2019:未解析的外部符号"public: __thiscall cv::SURF::SURF(void)"(??0SURF@cv@@QAE@XZ)参考function _main c: users user desktop project prjprjsh1.obj撮合下

#include <opencv2imgprocimgproc_c.h>
#include <stdio.h>
#include <math.h>
#include <opencvhighgui.h>
#include <opencvcv.h>
#include <opencv2/features2d/features2d.hpp>
#include <opencv2/calib3d/calib3d.hpp>
#include <opencv2/core/core.hpp>
#include <opencv2/nonfree/features2d.hpp>
using namespace cv;
void main(){
char i; 
Mat image,img,ref;
ref=imread("hh.jpg");
// create window to show image 
namedWindow("window", CV_WINDOW_AUTOSIZE);
namedWindow("costel", CV_WINDOW_AUTOSIZE);
namedWindow("fanel", CV_WINDOW_AUTOSIZE);
Mat ig,ib,ibb;
Mat bkg;
Mat prev;
Mat stor;
cvtColor(ref, ref, CV_BGR2GRAY);
FastFeatureDetector detector(15);
vector<KeyPoint> keypoints1;
detector.detect(ref, keypoints1);
SurfDescriptorExtractor extractor;
Mat descriptors1;
extractor.compute(ref, keypoints1, descriptors1);
....