archiver not allowing multi-file downloads

[mrvelous01]

I am trying to enable multi-file downloads, optionally with compression. I added "archiver" plugin to /backend/configuration.php but nothing is showing up but the basic download dialog when multiple files are selected. I have tried all 3 available COMPRESSOR options but no difference. Please advise.

...
"Archiver" => array(
"compressor" => "native",
"enable_download" => TRUE,
"enable_compress" => TRUE,
"enable_extract" => TRUE
),
);
?>