[Exim] LDAP Lookups + Exim4

I am currently undergoing a migration from Exim 3 to 4.
I compiled Exim4 with the OpenLDAP2 libraries without a hitch. Now I am
trying to convert my configuration file.
Apparently this Router is not syntatically correct:
external_ldap_aliases:
driver = redirect
search_type = ldapm
query = ldap://ldap.doc.state.vt.us/ou=Groups,o=Vermont Department of
Corrections,c=US?rfc822MailMember?sub?(cn=${local_part})
file_transport = address_file
pipe_transport = address_pipe
unseen

And one know how I can rewrite this or point me to some documentation on
how to write LDAP enable routers

Thanks,
Joseph Kezar