I have syntax-corrected your snippet (Missing semi-colon, comma, bogus NULL), and removed non-existant noise parameters.

use strict;

writeeventlog();
######################################

sub writeeventlog {

   use Win32::EventLog;
   my $eventLog = Win32::EventLog->new('MyProgram');

   my %eventRecord = (
           #'Source' => undef,
           #'Computer' => undef,
           'Category' => 0, #NULL,
           'EventID' => 0,
           'EventType' => EVENTLOG_ERROR_TYPE,
           'Strings' => 'Test.',
           'Data' => 'Test.',
           );

   $eventLog->Report(\%eventRecord);
   $eventLog->Close();
}
[download]

This writes entries to the event log just fine. The source does NOT haveto be registered in the Registry, but you can follow shonorio's advice.

The Eventviewer message is an attempt to decode the EventID, but since you do not have a message file or DLL associated with your app, you will need to ignore the Event viewers failed attempt to provide a "description" for your eventID.