Embedding data from a text file into DWT subband using steganography

Question

I am attempting to embed data from a text file(which contains only numeric data) into LL subband of an image using a steganography. I am getting an error "Error using bitset ASSUMEDTYPE must be an integer type name" in the line of code:

L(ii,jj)=bitset(L(ii,jj),1,stego(ii,jj));

I have attempted to run in debugger but I am having no luck. I think it must be something to do with the data type of L?? I have tried changing image to binary,double etc but I still get this error! Please can someone give me some advice on where I am going wrong?I have a insert my code below

 % loading cover image
img=imread('lena.bmp');
image=im2double(img); 


% get DWT of image
[LL,LH,HL,HH] = dwt2(image,'haar');

A = importdata('minutiaTest.txt');
I = dec2bin(A,8);

L=LL;

% determine size of LL subband 
Mc=size(L,1);   %Height
Nc=size(L,2);   %Width


% determine size of message object
Mm=size(I,1);   %Height
Nm=size(I,2);   %Width


for ii = 1:Mc
    for jj = 1:Nc
        stego(ii,jj)=I(mod(ii,Mm)+1,mod(jj,Nm)+1);
    end
end


for ii = 1:Mc
    for jj = 1:Nc
       L(ii,jj)=bitset(L(ii,jj),1,stego(ii,jj));
    end
end

stego_image = idwt2(LL,LH,HL,HH,'haar');
imwrite(uint8(stego_image),'stego.bmp');
figure; imshow(stego_image,title('Stego image'));