Try reading your csv files with Text:CSV_XS, adding use strict; use warnings and some print diagnostics.

#!perl
use strict;
use warnings;
use Spreadsheet::WriteExcel;
use Text::CSV_XS;

my $csv = Text::CSV_XS->new({ 
  binary => 1, sep_char => ',', eol => "\n"}); 
  
my $xlsfile = 'c:/temp/xyz_stat1.xls';
my $workbook = Spreadsheet::WriteExcel->new($xlsfile) 
   or die $!;

my $num_files = $ARGV[0] || 0;
for my $k (1..$num_files){
  my $csvfile = $ARGV[$k];
  print "Opening $csvfile .. ";
  open my $fh, '<', $csvfile or die "Cannot open $csvfile : $!"; 
  my $sheet = $workbook->add_worksheet('sim_'.$k);
  my $ar = $csv->getline_all($fh);
  $sheet->write_col(0,0,$ar);
  close $fh;
  print scalar (@$ar). " lines read into sheet sim_$k\n";
}
$workbook->close;
print "$xlsfile created\n";
[download]

poj