[exim] Help with expansion condition for an autenticator wit…

I am encountering considerable difficulty with an expansion condition on
an authenticator:

I have 2 conditions each of which works on its own on the RHS of a
server_condition in an authenticator. the conditions are:

${if
crypteq{$auth3}{\{crypt\}${lookup{$auth2}lsearch{/usr/local/src/exim/etc/mail/our-passwords}{$value}fail}}}

and

${if ldapauth
{user="uid=${quote_ldap_dn:$2},ou=people,dc=lcu,dc=ac,dc=uk"
pass=${quote:$3} ldap://dir-server.lcu.ac.uk/ } }

As said both work on their own. However when I try to combine them with
an or statement things break. I am missing something here quite
fundamental. Can anyone assist?

What I want Exim to do is to check the passwords in the file first and
then only if that yealds a false result go off and check the LDAP server.

I thought a or{{Condition1}{Condition2}} would do the trick but it
appears not to work. but combining them with this gives result of the
expansion
or {{true}{true} which is not "true".

Kittos

Rob