Managed Backups Failure

I have Snapshot installed on this site with managed backups enabled, but the managed backups keep failing. I got an email from WPMUDev regarding this problem saying that there was an "error when attempting full site backup."

I've been having the same problem with a related site on the subdomain portal.evanhcpa.com.

I would appreciate it if you could help with this issue so that I can backup these two sites.

Thanks,

Eric Hilton