Opencv --- I cannot use the function imread

Opencv --- I cannot use the function imread

I have a problem in opencv function. I can use IplImage* img =
CvLoadImage("2_DeepViewOutput.png");
However I can not use
Mat img = imread("2_DeepViewOutput.png");
It gave me
Multiple markers at this line - Line breakpoint: Hello.cpp [line: 11] -
undefined reference to `cv::imread(std::string const&, int)'
I think I have loaded the library in the path. I did not the reason,
please help me.
THANKS