Your problem lies in the line:

$fh = $query->upload('$filename');
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You have single quotes around $filename, thus preventing it from being interpreted. Get rid of them.

$fh = $query->upload($filename);
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What it looks like is happening is that it was looking for a file field named, literally, '$filename'. It wasn't finding one-- yet the file got uploaded OK, so there was no error message. (I'm not sure why your "CENTER" tag didn't appear, though.) The following idiom might be clearer:

eval {
    ## ...

    $fh = $query->upload($filename) 
            or die "No file uploaded: '@{[ $query->cgi_error() ]}'";

    ## ...
};
$@ and do {
     print_html($@);
};
[download]

stephen