...
        my $row;
        @$row = split(/,/, $line );
        push @$sheet2 , $row;
        ...


##</code><code>##

    ...
    my @row = ();
    @row = split(/,/, $line );
    push @sheet2 , \@row;
    ...


##</code><code>##

   ...
   push @sheet2, [ split(/,/, $line ) ];
   ...