How can resolve this problems with fft?

Friends have the following problem I'm doing the enhanced fingerprint with FFT and i have done the following code

if true
  % code
clear all,close all,clc;
k=0.45;
I = imread('database/101_1.tif');
I = 255-double(I);
[u v] = size(I);
u1=floor(u/32)*32;
v1=floor(v/32)*32;
IN = zeros(u1,v1);
for ii =1:32:u1
  for jj=1:32:v1 
  l_a =ii+31;
  l_c =jj+31;

    FFT=fft2(I(ii:u1,jj:v1));

    factor = abs(FFT).^k;
    block = abs(ifft2(FFT.*factor));
    max_block =max(block(:));
    if max_block==0
    max_block=1;
    end
    block = block./max_block;
    IN(ii:l_a,jj:l_c)=block;
    end
end

end

now this give me the following error: Subscripted assignment dimension mismatch.

Error in inpressoes2 (line 43) IN(ii:l_a,jj:l_c)=block;

someone can help me?