Hi. I am trying to create a loop for adaptive feedback cancellation. While the code runs without an error, i am not getting any output. Can anyone please help correct my mistake? Thank you in advance :)

[x,f,nbit]=wavread('tapestry.wav');

fb=zeros(length(x),1); %feedback signal, output of original feedback path F(k)

y=zeros(length(x),1);y(1)=x(1); %mic input

v=zeros(length(x),1); %adaptive filter input

u=zeros(length(x),1);u(1)=5*x(1)%loudspeaker signal initialized when there's no feedback signal at the start

e=zeros(length(x),1);e(1)=x(1); %error signal, i.e. e(n) = y(n)-v(n)

F=dsp.DigitalFilter; %original feedback path F(k), FIR filter of order 50

F.TransferFunction='Fir (all zeros)';

F.Numerator=fir1(50,[0.5,0.75]);

F.FrameBasedProcessing=false; %enables sample-by-sample processing

%fvtool(F.Numerator,1); %displays magnitude response of F(k)

AF=dsp.LMSFilter;

AF.Method='Normalized LMS';

AF.Length=50;

AF.StepSize=0.002;

for i=2:length(x)

    fb(i)=step(F,u(i-1));      
    [v(i),err,wts]=step(AF,u(i-1),fb(i-1));   
    y(i)=x(i)+fb(i);   
    e(i)=y(i)-v(i);   
    u(i)=5*e(i);   
 end