help me to find transfer function for one sensor

%  Input
assignin('base', 'PClean_f',eval(['PClean_',num2str(ii)]));

[SPClean]      = fft(PClean_f);

%  Output

assignin('base', 'Pdisturbed_f',eval(['Pdisturbed_',num2str(ii)]));

[SPdisturbed]      = fft(Pdisturbed_f);

I am not getting the expected results for 1 particular sensor,I have calculated transfer function for 20 different readings and now in this program i am importing the those 20 T.functions and averaging them to get a unique transfer function that in frequency domain would give A=A=TF.*SPdisturbed;

and B=ifft(A);.....here the obtained * B == Pclean signal * but i am not getting so

reading=20

for q = 1:readings

      filename = sprintf('Tfunct%d_%d.mat',sn,q);

      TF = importdata(filename);

      TFtrans=transpose(TF(1:end,1));

      T(q,1:end)=TFtrans;

 end

 % TF=T';

 T_f_trans=mean(T); %Taking mean of T i.e. all TF from 1 TF1 to TF5

 TFinal=transpose(T_f_trans);

 A=TF.*SPdisturbed;

 B=ifft(A);

 J=norm(abs(PClean)-abs(B));