After dividingwatermarked video into no. of frames not getting watermaked frames. Please help

Hi, My PG project title is "Invisible video watermarking for data integrity and security based on DWT". My work is 80% completed except dewatermarking. I divided original video into no of frames. After that i applied watermark on each frame. Now when i tested that watermark is ther on these frames or not, then i found watermark by dewatermarking module. So further i created watermarked video from these image sequence. This watermarked video is send to receiver. no at receiver side i again divided video into frames to check whether watermark exists on frames or not. but although this watermaked video created from watermaked frames. After dividing same video why I am not getting watermarked frame? Please help me.

My code for dividing video into frames-

originalVideo = VideoReader(a);

for ii = 1:originalVideo.NumberOfFrames

    img = read(originalVideo,ii);
end

My code to again create video from watermaked images-

%read video from image sequence

imageNames = dir(fullfile(workingDir,'images','*.png'));

imageNames = {imageNames.name}';

imageStrings = regexp([imageNames{:}],'(\d*)','match');

imageNumbers = str2double(imageStrings);

[~,sortedIndices] = sort(imageNumbers);

sortedImageNames = imageNames(sortedIndices);

%disp(sortedImageNames(1:380));

outputVideo = VideoWriter(fullfile(b));

outputVideo.FrameRate = originalVideo.FrameRate;

open(outputVideo);

for ii = 1:length(sortedImageNames)

   img = imread(fullfile(workingDir,'images',sortedImageNames{ii}));

   writeVideo(outputVideo,img);

end

close(outputVideo);