403 Forbidden response

Hi,
on my control panel for this plugin I’m getting the message: BackUpWordPress has detected a problem. wp-cron.php is returning a 403 Forbidden response which could mean cron jobs aren’t getting fired properly. BackUpWordPress relies on wp-cron to run scheduled back ups.

I still got the email with the back up but how can I get rid of this message to make sure everything is working fine?

anything to do with BulletProof security that I installed recently?

thanks !

http://ww.wp.xz.cn/extend/plugins/backupwordpress/