[exim] lookup syntax help - second try

I'm trying an experiment - but it somplains about the syntax.

missing lookup type

process_and_forward_auto:
driver = manualroute
domains = +preprocess_auto_domains
condition = ${if match{$h_X-Spam:}{HIGH}{no}{yes}}
transport = remote_smtp
route_list = * ${lookup dnsdb{a=mail-in.$domain}{$value}}

Yes - I have dnsdb compiled in.

What I'm trying to do is set it up so that if the MX pints to my server
- AND - there exists a host called "mail-in.domain.com - then the router
will send the mail to that domain. If the host doesn't exist - I want to
skip the router and go to the next router. There may be a better way to
do this.