Even with both of those tweaks, the "Undefined subroutine CGI::optgroup" error still occurs ... Looking in CGI.pm, there is no optgroup() sub defined .. is it supposed to be available via AUTOLOAD?

Update: It seems to work for OP now, but I still get his original error:

use strict;
use warnings;
use CGI qw/:standard/;
my $q = new CGI;
$q->optgroup();
__END__
Undefined subroutine CGI::optgroup
 at /tmp/c line 6
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Update: Yup, it's cause i was working of an old (2.752) version.