Error in optimization with GA: Struct contents reference from a non-struct array object

Hi, I'm new to Matlab and Simulink. I am going to optimize my Simulink model using the genetic algorithm.

The optimization can run, but it does not work at the plot of the results for each GA-generations. When the optimization ends, I can not obtain the best result with the optimal variables. The only thing is an error:

Error running optimization. Struct contents reference from a non-struct array object.

Here is my function:

 function grades = rules(Vars)
 ........
 ........
 % Data from Simulink model
 [y] =sim('Model',1000);

 % Data are imported from Data file
 load('uH.mat');

 x_d = y(1:8001,1);
 x_ud = uH(1:8001,2);

 RMS_1 = sqrt(sum(x_d.*x_d)/8001);
 RMS_2 = sqrt(sum(x_ud.*x_ud)/8001);

 % fitness function
 grade_RMS_x = (RMS_x_ud - RMS_x_d) / RMS_x_ud;
 grades = 1 - grade_RMS_x;

 end

It would be perfect if someone could help me out. :) Thank you so so much!

[Walter Roberson]

Is uH.mat being written by the model using a ToFile block? Then if so note that the default is to write as a Timeseries object https://www.mathworks.com/help/simulink/slref/tofile.html and that even if you specify Array that the first column will be timestamps.

[Junyu Chen]

sry, no. uH.mat is imported from an external file. :(