Please help. How to solve this m-scripting error?

??? Error using ==> add_block
Invalid destination block specification.

This is my script and creating a model to add block into it.

I am reading a '.xlsx' file;

sys = 'testModel';

new_system(sys) 

open_system(sys) 

filename = 'abc.xlsx';

[x,y]= xlsread(filename);

[row,col]= size(y); // [38,4]

   i = 1: col  // 1: 4
     m= y(:,i); // y(:,1) reads 1st full column
     n = m';  // arranging the column in vector matrix for ease
     k = length(n) // 38
     for 1 = 1: k // 1: 38
       count = 0;
       x = 30+count;
       y = 30+count;
       w = 30+count;
       h = 30+count;
       pos = [x y+h/4 x+w y+h*.75]
       add_block('built-in/Inport',[sys n(k)],'Position',pos);
       count = count+10;
  end

iam getting this error:

??? Error using ==> add_block
Invalid destination block specification.