Matlab中出现FileIO was not loaded from the file.

[heluo240808]

最近用matlab 写了一个程序，涉及到文件的频繁读取操作，当读了2000多次后，出现下面的提示：
Caught "std::exception" Exception message is:
Message Catalog MATLAB:FileIO was not loaded from the file. Please check file location, format or contents
具体代码如下：

function getSiftValue
	father = 'D:\users\luo_he\DATA';
	mkdir(father, 'desData');
	mkdir([father, '\', 'desData'], 'tempTrain');
	mkdir([father, '\', 'desData'], 'tempTest');
	Train = [father, '\', 'tempTrain'];
	Test = [father, '\', 'tempTest'];
	siftTrn = [father, '\', 'desData', '\', 'tempTrain'];
	siftTst = [father, '\', 'desData', '\','tempTest'];
	subTrn = dir(Train);
	lenTrn = length(subTrn);
    if isunix
        command = '!./sift ';
    else
    command = '!siftWin32 ';
    end
    command = [command ' <tmp.pgm >tmp.key'];
	%classDescriptors = [];	
	for i = 3 : lenTrn
		className = subTrn(i).name;
		imgNames = dir([Train, '\', className]);
		imgNum = length(imgNames);
		%open a file to save class descriptors
		fileName = [siftTrn, '\', [className, '.des']];
		classDes = fopen(fileName, 'a');
		fprintf(classDes, '[type:sift]\n');
		%fclose(classDes);
		for j = 3 : imgNum
			imgPth = [Train, '\', className, '\', imgNames(j).name];
			image = imread(imgPth);
			image = prcssImage(image);
			[rows, cols] = size(image);
            % in case of file open fail, try 10 times
            for x = 1 : 10
                f = fopen('tmp.pgm', 'w');
                if f ~= -1
                    break;
                end
            end
            if f ~= -1
                fprintf(f, 'P5\n%d\n%d\n255\n', cols, rows);
                fwrite(f, image', 'uint8');
                fclose(f);
                % Call keypoints executable
                eval(command);
                tmpkey = fopen('tmp.key', 'r');	
                keyData = fread(tmpkey);
                fclose(tmpkey);
                fwrite(classDes, keyData);
            else
                errfile = fopen([father, '\', 'error.txt'], 'a');
                fprintf(errfile, 'open tmp.pgm error, when computing %s', imgPth);
                fclose(errfile);
            end
       end
            fclose(classDes);
	end

	subTst = dir(Test);
	lenTst = length(subTst);
	for i = 3 : lenTst
		className = subTst(i).name;
		mkdir(siftTst, className);
		imgNames = dir([Test, '\', className]);
		imgNum = length(imgNames);
		for j = 3 : imgNum
			imgPth = [Test, '\', className, '\', imgNames(j).name];
			image = imread(imgPth);
			image = prcssImage(image);
			[rows, cols] = size(image); 
			fileName = [siftTst, '\', className, '\',imgNames(j).name, '.des'];
			imgDes = fopen(fileName, 'a');
			fprintf(imgDes, '[type:sift]\n');
			%fclose(imgDes);
            for x = 1 : 10
                f = fopen('tmp.pgm', 'w');
                if f ~= -1
                    break;
                end
            end
            if f ~= -1
                fprintf(f, 'P5\n%d\n%d\n255\n', cols, rows);
                fwrite(f, image', 'uint8');
                fclose(f);
                % Call keypoints executable
                eval(command);
                tmpkey = fopen('tmp.key', 'r');	
                keyData = fread(tmpkey);
                fclose(tmpkey);
                fwrite(imgDes, keyData);
             else
                errfile = fopen([father, '\', 'error.txt'], 'a');
                fprintf(errfile, 'open tmp.pgm error, when computing %s', imgPth);
                fclose(errfile);
             end 
		end
    end

是在进行第二个大的for循环出现的问题，觉得不可能是文件出现的问题呀，因为之前对文件都执行上千次操作了，都没有问题。
这个问题困扰我好久了，希望有人能解惑。