Hi Im trying ti run this code but im getting "??? Cell contents assignment to a non-cell array object. Error in ==> dataemb at 29 HEAD{POS}=Data{i}; " can anybody help me out soon please...

 %%Metadata to be Encoded
%  clc;
fid = fopen('m1.txt');
   inputimg = textscan(fid,'%s','delimiter','\n');
   lines =  inputimg{1,1};
   vecImg = reshape(inputimg,1,[]);
  Data = vecImg;
% %   inputimg = fread(file);imview('lena.jpg');
% %   vecImg = reshape(inputimg,1,[]);
% %   Data = vecImg;
% Perform Huffman Encoding
HEAD=0;
%--Compute Header--------
POS=0; 
S_=size(Data);        
for i=1:S_(2)
    if (POS~=0)
      S=size(HEAD); F=0;
      k=1;
      while (F==0 && k<=S(2))
         if (Data(i)==HEAD(k))  F=1; end;
         k=k+1;
      end;
    else F=0; 
    end;

    if (F==0)
      POS=POS+1;
      HEAD{POS}=Data{i};
    end;
end;
fprintf('Header:\n');
display(HEAD);
%%%%%%%%Compute probability for symbols%%%%%%%%%%%%
S_H=size(HEAD);
Count(1:S_H(2))=0;
for i=1:S_H(2)
    for j=1:S_(2)
        if (Data(j)==HEAD(i))
            Count(i)=Count(i)+1;
        end;
    end;
end;
Count=Count./S_(2);
fprintf('probability for symbols\n');
display(Count);
%%%Sort accoridng to maximum number%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
for i=1:S_H(2)-1
    for j=i+1:S_H(2)
        if (Count(j)>Count(i))
            T1=Count(i); Count(i)=Count(j); Count(j)=T1;
            T1=HEAD(i); HEAD(i)=HEAD(j); HEAD(j)=T1;
        end;
    end;
end;
fprintf('Sort Results\n');
display(HEAD);
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
[dict,avglen] = huffmandict(HEAD,Count); % Create dictionary.
hcode = huffmanenco(Data,dict); % Encode the data.
display (hcode);
% %Cover Image
img = imread('images.jpg');imview('images.jpg');
sX=size(img);
% Discrete Wavelet Transform
[LL LH HL HH]=dwt2(img,'haar');
dec=[LL,LH
    HL,HH    
    ];
figure;imshow(dec,[]);title ('DWT');
%Embedding Image in 3 X 3 bit Propagation
% Selected Band is HH.
b = 3;
txt = hcode;
I = LL;
N = 8*numel(txt);
S = numel(I);
if N > S
    warning('Content Truncated')
    txt = txt(1:floor(S/8));
    N = 8*numel(txt);
end
p = 2^b;
h = 2^(b-1);
I1 = reshape(I,1,S);
addl = S-N;
dim = size(I);
I2 = round(abs(I1(1:N)));
si = sign(I1(1:N));
for k = 1:N
    if si(k) == 0
        si(k) = 1;
    end
    I2(k) = round(I2(k));
    if mod((I2(k)),p) >= h
        I2(k) = I2(k) - h;
    end
end
bt = dec2bin(txt,8);
bint = reshape(bt,1,N);
d = h*48;
bi = (h*bint) - d;
I3 = double(I2) + bi;
binadd = [bi zeros(1,addl)];
I4 = double(si).*double(I3);
I5 = [I4 I1(N+1:S)];
img = reshape(I5,dim);
%img = embedAction(double(HH),hcode,3);
%Perform Inverse Wavelet Transform
X = idwt2(img,LH,HL,HH,'haar',sX);
figure;imshow(uint8(X));title('IDWT');
% Writing Embedded Image file
imwrite(uint8(X),'embed.jpg','jpg');
figure;
imshow(uint8(X));title('EMBEDDED OUTPUT');