A cell can be defined but blank. Try this test code

#!perl
use strict;
use Spreadsheet::ParseExcel;

my $filename = "Book2.xls";
my $e = new Spreadsheet::ParseExcel;
my $eBook  = $e->Parse($filename);
my $eSheet = $eBook->{Worksheet}[0];

for my $row (1 .. $eSheet->{MaxRow}){
  for my $col (1 .. $eSheet->{MaxCol}){
    if (defined $eSheet->{Cells}[$row][$col]){
      my $val = $eSheet->{Cells}[$row][$col]->Value;
      print "$row $col = '$val'\n";
    } else {
      print "$row $col Not defined\n";
    }
  }
}
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