@Carl Love It works! Thanks a lot.

Hi, @tomleslie . I have modified the code as follows. But the problems still exists.

elenum :=numelems(theDiagnosis[1][1]);
faultcom={};
faultloc={};
if elenum = 1 then
    faultcom := theDiagnosis[1][1][1][1];
    faultloc := theDiagnosis[1][1][1][2];
else
    for numi from 1 to elenum do
        faultcom := faultcom union theDiagnosis[1][1][numi][1];
        faultloc := faultloc union theDiagnosis[1][1][numi][2];
    end do;
end if;

@Lenin Araujo Castillo Thanks for your reply. Carl Love  have helped me sove it.

@Carl Love Thanks, I know how to solve it.

@rlopez Thank you! I will try it.