Please add this line :
chmod 0666,"$db_script_path/backup/$date.links.db","$db_script_path/backup/$date.category.db","$db_script_path/backup/$date.email.db" ;
after this code:
print "\tBacking up links, category and email database (File::Copy) ... \n";
&File::Copy::copy ("$db_script_path/data/links.db", "$db_script_path/backup/$date.links.db") or &cgierr ("Unable to copy links backup. Reason: $!");
&File::Copy::copy ("$db_script_path/data/categories.db", "$db_script_path/backup/$date.category.db") or &cgierr ("Unable to copy category backup. Reason: $!");
&File::Copy::copy ("$db_script_path/data/email.db", "$db_script_path/backup/$date.email.db") or &cgierr ("Unable to copy email backup. Reason: $!");
in the build_backup function in the nph-build.cgi

Hope with this help,

Mark