writing coeffcients to a wavelet packet tree in MATLAB

Question

I am trying to create an empty wavelet packet tree and filling up its terminal nodes with coefficients. In short following is my simple code :-

clc,close all,clear all;
img = imread('barbara.png');
T = wpdec2(img,2,'db4');
T2 = cfs2wpt('db4',size(img),tnodes(T),4);
u = tnodes(T);
for i = 1:length(u)
    x = read(T,'cfs',u(i));
    write(T2,'cfs',u(i),x);
end

However when I display T2, i find that its terminal nodes contain no information except Zero matrics of appripriate sizes .. What is the reason and how do I correct this problem ?