How do i fix the error titled ''Unexpected exception (Package is not open) was caught''?

Hello I am doing a simulation and i am trying in a script to run the simulink model and get result of an output for different parameter.

clc

clear all

close all

%Define parameter sets

iteration=275;

K_sweep=linspace(0.39,0.63375,275);

simout=cell(1,iteration);

%run the simulation command in a loop and collect the simualtion results

for idx=1:length(K_sweep)

%load Simulink model

load_system('MyMODEL');

set_param('MyMODEL/ESR','Resistance',num2str(K_sweep(idx)));

simout{idx}=sim('MyMODEL');

v122=V12(1:20920,1);

%Store values into

sad(:,idx)=v122;

end

but i get this error (though the simulation work and takes a few data and store them into the sad but then crashes)

the error is ''Unexpected exception (Package is not open) was caught''.

Can someone please tell me how can i fix this?