Using a file with sender_net_reject

I'm trying to configure a lookup file with the "sender_net_reject_recipients"
option, but exim complains at startup with :

error in IP net specification lsearch;/usr/local/exim/tables/ip_banned in
sender_net_reject_recipients option

The file file exists and has 644 permissions. I've configured an empty
"sender_host_reject_recipients" file with no problem. I've also tried putting
entries into the file, but get the same error message.

I've put IP addresses directly into the configure file and this works fine.
Not what I want though, so...any ideas?

Thanks,

John.

***************************************************************************
John Horne,                                  E-mail: J.Horne@???
Computing Service,                           Phone : +44 (0) 1752 233911
University of Plymouth, UK.                  Fax   : +44 (0) 1752 233919

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