[Exim] host_accept_relay

Hello all,

    I've recently had a problem with the  host_accept_relay   option,
being that I cannot use a command like

host_accept_relay = lsearch;/usr/local/etc/exim/relay-access
    when relay-access contains:
192.168.0.0/24
10.10.10.0/24

etc. But if I use
host_accept_relay = 192.168.0.0/24

It works.

Is there a reason why its not possible to use the lsearch method?
And if so is there any other way I could do this as I need to use a
file.

Am I doing something wrong?

Thanks in advance,
Dave.