Modalsd not using all my data

Hi eveyone,

I have a problem using modalsd because when I use it only use half of my frf but I don't know why. I have tried changing number of modes and my data but nothing change..

If someone can help me with this I will be really gratefull.

Here is my code

close all

winlen = 100;
fs = 1251;
frf = [imp_1_cpt2(:,2),imp_3_cpt2(:,2),imp_4_cpt2(:,2),imp_6_cpt2(:,2),imp_7_cpt2(:,2),imp_9_cpt2(:,2),imp_10_cpt2(:,2),imp_12_cpt2(:,2),imp_13_cpt2(:,2),imp_15_cpt2(:,2),imp_16_cpt2(:,2)];
f = linspace (1,length(imp_1_cpt2),length(imp_1_cpt2));

ft = modalsd(frf,f,fs,'MaxModes',30,'FreqRange',[0 1251]);

Physfreq = ft(28,[ 2 4 9 10 15 21 25])
[fn,dr,ms] = modalfit(frf,f,fs,10,'PhysFreq',Physfreq,'FitMethod','lsrf');
% Définition des déformées modales
defor_mod_test = imag(ms); 
save defor_mod_test.mat
figure(4)
title('Déformées modales')
plot(defor_mod_test(:,1),'-ok'),hold on 
plot(defor_mod_test(:,2),'-or'),hold on 
plot(defor_mod_test(:,3),'-og'),hold on 
plot(defor_mod_test(:,4),'-ob'),hold on 

And here is the result