getting error using canny edge detector

edit

I do not know why I get error in this line:

Canny( dst_Gaussian, dst_Gaussian, 100, 100*3, 3 );

everything seems correct but I get "Unhandled exception.." error.

This is what I am trying to do:

    cv::Mat dis = Mat(width, height, CV_32FC1, dises);
    cv::Mat dst_Gaussian(width, height, CV_32FC1);
    Mat dst_Canny;
    dst_Gaussian= dis.clone();
    dst_Canny.create( dis.size(), dis.type() );

//  

blur( dis, dis, Size(3,3));

    GaussianBlur( dis, dst_Gaussian, Size( 3, 3 ), 2, 2);
    imshow("Gaus",dst_Gaussian);

    //findContours(dst, contours, hierarchy, int mode, int method, Point offset=Point());
    Canny( dst_Gaussian, dst_Gaussian, 100, 100*3, 3 );
     dst_Canny = Scalar::all(0);

    dis.copyTo( dst_Canny, dst_Gaussian);
    imshow("canny", dst_Canny);

"dises is a pointer."

Thanks in advance