Error message when making Backup

Hello,

I have the problem when I make a Backup for my Wordpress site, then I notice a error message or backup-warning

{"php":{"cf8718b502f36d9bc4fbeb406974af14":"Undefined index: access-id, \/home\/5493\/www.nativum.at\/wp-content\/plugins\/wpmu-dev-seo\/wds-files\/wds-seomoz\/wds-seomoz-results.php, 21"}}

Please could you give me a advice how to fix it,

regards,

Klemens