“OpenCvSharp.OpenCVException”类型的未经处理的异常在 OpenCvSharp.dll 中发生 !_img.empty()

      Mat src = new Mat(@"C:\Users\admin\Desktop\ImageServer\pic\reveive.jpg", ImreadModes.Grayscale);
        Mat result = src.Threshold(150, 255, ThresholdTypes.Binary);
        result.SaveImage(@"C:\Users\admin\Desktop\ImageServer\pic\BinaryPic.jpg");
        Cv2.WaitKey(0);

请大家分析一下什么问题
在重装系统以及vs后重新打开原有项目opencvsharp.dll就一直报错不知是否有关