[Exim] Failed to expand condition ....

Hi,

I have some problems making exim looking up thing in a dbm file. I hjave
created a dbm file with users and passwords in it and I wan't exim to check
that database to see if a username is in it or not. If it is in it he must
send mail to that user and if it isn't in the file he has te send an error
back.

I added the fellowing line to my conf:

condition = ${if {${lookup{$local_part}dbm{/etc/users}{$value}}}

But i still get the error:

failed to expand confdition "${if
{${lookup{$local_part}dbm{/etc/users}{$value}}}" for localuser director:
"pwd2" is not a number

that pwd2 is the password for the user i am trying to mail.

Any ideas????

Thierry Martens