[exim] lookup syntax question

Hi again folks.

I have a lookup of aliases in non-standard (not our core) domains. The first
one *always* works as expected.

The second one works when I text it using "exim -bt" and usually works for
live emails. However, sometimes it fails.

Any ideas why?

Version 1:

   condition      = ${if eq 
{${lookup{$local_part}lsearch{/etc/aliases.d/$domain}{found}{notfound}}}\
                             {notfound}\
                             {yes}{no}\
                            } 

Version 2:

condition = ${lookup{$local_part}lsearch{/etc/aliases.d/$domain}{yes}{no}}

The fill clause is:
  deny    message = unknown recipient $local_part in $domain
      log_message = unknown recipient $local_part in $domain from 
$sender_address
      domains = +non_std_domains
      condition = ${lookup{$local_part}lsearch{/etc/aliases.d/$domain}{yes}{no}}

Even though the user exists, the lookup sometimes fails - for the same
$local_part value

Here is a log entry:

2014-04-28 15:22:33 H=smarthost2.mail.uk.easynet.net [212.135.6.12]
F=<xxxxxxx.xxxxl@???> rejected RCPT <lllll@ddddddddddddd>: unknown
recipient lllll in ddddddddddddd from xxxxxxxxxxxxl@???

--
Gary Stainburn
Group I.T. Manager
Ringways Garages
http://www.ringways.co.uk