Check the variable radioNum ...it might be either negative or double 0....MATLAB accepts only posititve integers as indices...zero cannot be an index.
A = rand(10,1) ;
A(1) % no error
A(logical(0)) % no error because index can be logical 0 / 1
A(-1) % error becuase index cannot be negative
A(0) % error because index cannot be zero (double)
