There is a Bug in the admin_html.pl, here you will find this code:
open (MODIFY, "<$db_modified_name") or &cgierr("unable to
open validation file: $db_valid_name. Reason: $!");
But it should say:
open (MODIFY, "<$db_modified_name") or &cgierr("unable to open validation file: $db_modified_name. Reason: $!");
Then it gives your an incorrect data, instead the 'validate.db' file that sure is in your directory, the file that is mising is the 'modified.db'
Cheers.
Miguel