Can't locate object method "pool" via package "Apache2::Filter"... line xx

Greetings,

I'm relatively new to mod_perl, so please forgive the ignorance.

I've managed to create an output filter, but I'm having a problem with an
input filter.  The error I get is as per the subject line.

Here's the code:

apache config

Perlrequire /opt/code/scripts/apache2-perl-startup.pl
...
PerlOutputFilterHandler ZCRM::OFilter::output
PerlInputFilterHandler ZCRM::OFilter::input

And here's the perl code (output filter works fine, but the input
filter results in the error below)

package ZCRM::OFilter;

use strict;
use warnings;

use Apache2::Filter     ();
use Apache2::RequestRec ();
use Apache2::Const -compile => qw(OK DECLINED MODE_READBYTES);
use APR::Const -compile => qw(SUCCESS BLOCK_READ);
use Apache2::Connection ();

use constant IOBUFSIZE  => 8192;

use strict;

sub output {
    my $f = shift;
    my $r = $f->r;

    while ( $f->read( my $buffer, 1024 ) ) {
        # do work on $buffer...
        $f->print($buffer);
    }

    return Apache2::Const::OK;
}

sub input {
    my $r = shift;

    my $bb = APR::Brigade->new( $r->pool,
$r->connection->bucket_alloc);  # <--- Line XX - ERROR here

    my $data     = '';
    my $seen_eos = 0;
    do {
        $r->input_filters->get_brigade( $bb, Apache2::Const::MODE_READBYTES,
            APR::Const::BLOCK_READ, IOBUFSIZE );

        for ( my $b = $bb->first ; $b ; $b = $bb->next($b)) {
            if ( $b->is_eos ) {
                $seen_eos++;
                last;
            }

            if ( $b->read( my $buf ) ) {
                $data .= $buf;
            }

            $b->remove;    # optimization to reuse memory
        }
    } while ( !$seen_eos );

    $bb->destroy;

    return $data;
}

1;

I would appreciate any pointers.

Thanks
Henk