I've made code for face recognition, but I get this error. Can anyone help me?

Here is my code:

function histSLGS = FP_FaceRecognition_Neat

directory = uigetdir;

imageVolum = [];

for i = 1:23

%imageVolume = [];

%directoryFinal = cell(23,1);

garing = '\';

extension = '.txt';

strI = num2str(i);

directoryFinal = strcat(directory,garing,strI);

fileList = dir(directoryFinal);

%fl = fileList

%DF = directoryFinal

%a = numel(fileList)

for idx = 3:numel(fileList)

tempImage = imread(fullfile(directoryFinal, fileList(idx).name));

imageVolum(:,:,:,idx) = tempImage;

end

%sI = size(imageVolum)

for j = 3:33

strJ = num2str(j);

garis = '_';

fileNameFinal = cell(30,1);

fileNameFinal = strcat(directoryFinal,garing,strI,garis,strJ,extension);

imgManipulation3 = SLGS(imageVolum(:,:,:,j));

histSLGS = hist(imgManipulation3);

[rowhist, columnhist] = size(histSLGS);

%r = rowhist

%c = columnhist

%fn = fileNameFinal

fid = fopen(fileNameFinal, 'w');

for l = 1:rowhist

for k = 1:columnhist

fprintf(fid, '%.3f, ', histSLGS(l,k));

end

fprintf(fid, '\n');

end

fclose(fid);

histSLGS;

end

end

I got this error message: 

Unable to determine the file format.

Error in ==> FP_FaceRecognition_Neat at 18

tempImage =

imread(fullfile(directoryFinal,

fileList(idx).name));

Thanks.