i need help with discrete wavelet transform

I have this code but gives me error, what should i do?

clear all;

data1 = importdata('ismt12.txt'); X=data1.data; X=X'; EMG1 = X(7, :);

% stun=size(data,2);

for i=1:length (EMG1)

 % EMG1=data(:,i);
end
  [c,L]=wavedec(EMG1,4,'db3'); 

    cd1=detcoef(c,L,1);

     cd2=detcoef(c,L,2);

       cd3=detcoef(c,L,3);

       cd4=detcoef(c,L,4);

    ca4=appcoef(c,L,'db3',4);