saving and loading mat histogram [closed]

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i already have my histogram, now i want to save the histogram data and call it back to do comparison. But when I try to show the image of "histogram1" and "histogram2" it gives unhandled exception error. here's my code

// save file
Mat result1
Mat result2
cv::FileStorage fs("results_file.yml", cv::FileStorage::WRITE);
fs << "result1" << result1 ;
fs << "result2" << result2 ;
fs.release();

// load file
cv::FileStorage fs("results_file.yml", cv::FileStorage::READ);
Mat histogram1 ;
Mat histogram2 ;
fs["result1"] >> histogram1 ;
fs["result2"] >> histogram2 ;
fs.release();
imshow("histogram1",histogram1);
imshow("histogram2",histogram2);