I'm trying to plot a unipolar NRZ using app designer and there seems to be an error while try to press the push button. Can you help me find a way to solve this?

value = app.Button.Value;

clc;clear;

%NRZ unipolar line coding

n=[1 0 1 0];

%NRZ Pulse shaping

i=1;

t=0:0.001:length(n);

for j=1:length(t)

if t(j)<=i

y(j)=n(i);

else

i=i+1;

end

end

plot(app.UIAxes,t,y);