[Exim] problem with expansion

# exim -d+expand -be
> [Auto-Reply] ${quote:$header_subject}

failed to expand: $header_subject}
    error message: missing } at end of string - could be header name not
terminated by colon
failed to expand: [Auto-Reply] ${quote:$header_subject}
    error message: missing } at end of string - could be header name not
terminated by colon
Failed: missing } at end of string - could be header name not
terminated by colon

Hmm, what am I doing wrong here guys?

Nathan.

--
Nathan Ollerenshaw - UNIX Systems Engineer
ValueCommerce - http://www.valuecommerce.ne.jp/