[Exim] exim_tidydb

hi, when I run

$exim_tidydb /var/spool/exim retry

I get:


Exim retry database in spool /var/spool/exim
failed to open DB file /var/spool/exim/db/retry: Invalid argument

I get the same error when trying to tidy the wait-remote_smtp datebase.
I run the commands as root.

Any ideas? thanks much.