I reduced your code down to this

#!/usr/bin/perl
use strict;
use warnings;
use Archive::Zip qw(:ERROR_CODES :CONSTANTS);
my $zip = Archive::Zip->new();
my $fileToAdd = '12345678.pdf';
my $viewBillPath = 'a_path';
my $fileWithPath = "$viewBillPath\\$fileToAdd";

$zip->addFile($fileWithPath) or die "couldn't add $viewBillPath\\$file
+ToAdd\n";
[download]

and then stepped through it with the debugger. I found the addFile method successfully, stepped into it and all of its friends. Eventually the code did the right thing (it threw an error because it couldn't find the file) and exited. I am betting that the elided code does something to $zip that causes it to lose it blessed-ness.

At this point you have a couple of options:

• Fire up the debugger and tromp through the code
• Insert print statements liberally -- dump the ref($zip) and some identifying locational data -- and determine what is zapping $zip.

Either process will require you to more critically examine your code (to figure out where the next break-point or print-stmt goes). When I do this kind of analysis (usually) I end up with an "Aha! That's where it goes wrong" moment, and find my bug.

Good Hunting