[Exim] Weird problem getting header match in router

Very odd, and I can't work out why..

This works and the conditions succeeds:
condition = ${if match {$h_x-mailer:}{mPOP Web-Mail 2.19} {yes}{no} }

This doesn't:
  condition = ${if eq {$h_X-Mailer:}{${lookup mysql{select blocklists.blockval from blocklists,users,domains \
              where users.localpart = '${quote_mysql:$local_part}' \
              and domains.domain = '${quote_mysql:$domain}' \
              and domains.domain_id=blocklists.domain_id \
              and users.user_id=blocklists.user_id}{$value}fail} } {yes}{no}}

In debug mode, the latter returns:
87222 MYSQL using cached connection for localhost:(/tmp/mysql.sock)/vexim/vexim
87222 lookup yielded: mPOP Web-Mail 2.19
87222 ditch_hdrmailer router skipped: condition failure

Hmmmm. Help? :-/

--
Avleen Vig
Systems Administrator
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