modperl: HTML::Template not working inside handler

use Apache2::Const -compile => qw(OK);

    $hdlr->content_type('text/html');
    $hdlr->print("Handler started<br />");

    my $template    = HTML::Template->new( filename => "/templates/
main.tmpl");
    $hdlr->print("outputting template...<br />");
    $template->output();

    $hdlr->print("after main, now sending Apache 'OK'<br />");
    return Apache2::Const::OK;

all of the $hdlr->print statements are printed in the web browser, but
the contents of "/templates/main.tmpl" are not printed. I don't see
any errors in the Apache logs.

>  Hello everyone,
>
> I'm working on coding up a mod_perl handler, but am unable to get
> HTML::Template to output. Below is my current code:
>
> # file:MyHandler.pm
> #------------------------------------------------------------------
> package MyHandler;
>
> #Load some helpful functions
> use strict;         #strict tolerance for code
> use warnings;       #extra warnings in the log
> use Carp;           #verbose logging
> use diagnostics;    #more verbose logging
>
> #Loadup some functions for later use
> use HTML::Template;
>
> #Loadup functions involved in being a handler
> use Apache2::RequestRec ();
> use Apache2::RequestIO ();
> use Apache2::Request;
> use Apache2::Const -compile => qw(OK);
>
> #------------------------------------------------------------------
> #
> # Subroutines
> #
>
> sub handler {
>     my $hdlr = shift;
>     $hdlr->content_type('text/html');
>     $hdlr->print("Handler started<br />");
>
>     my $template    = HTML::Template->new( filename => "/templates/
> main.tmpl");
>     $hdlr->print("outputting template...<br />");
>     $template->output();

    $template->output(print_to => $hdlr);