Content-Disposition

Hello,
 
I'm guessing there is a real simple answer to my question but as uasual, I can't find it :)
 
Simply put I'm trying to create a Zip file and push it to the user using a filename I've defined. Everything works except the name of the file that comes up in the browser dialog. It always defaults to the script/location name. I thought that all I needed was Content-Disposition but that doesn't seem to be working.
 
CentOS 5.5, mod_perl 2.0.4, apache 2.2.3 (both mod_perl and apache should be backported via yum update).
 
my $zip = Archive::Zip->new();
my $member = $zip->addString('yadda yadda yadda');
my $download_name = 'download.zip';
if ( $zip->writeToFileNamed('someothernamed.zip');
    open(ZIP, 'someothernamed.zip') or die "could not open sonz $!";
    binmode ZIP;
    my $output = do { local $/; <ZIP> };
    close(ZIP);
    $r->content_type('application/zip');
    $r->header_out( 'Content-Disposition' => 'inline; filename="' . $download_name . '"');
    $r->send_http_header;
    print $output;
    return Apache2::Const::OK;
}
 
I tried setting the header before the content_type and with and without "send_http_header". What am I doing wrong? How can I get the user to be prompted to save the file as "download.zip??
 
TIA!