It started off as a "Log folder '/var/www/vhosts/xxxxx.com/httpdocs/blog/wp-content/backwpup-8c90f-logs/' is not writeable!" error. So I went looking around and found a post that said to check php-safe mode. I checked mine and it is set to off. So next I increased the permissions on that directory to 775 and then to 777 when that didn't work. So that error went away. Next I got the error: "Backup folder not writeable!", so I went and changed that folder to 777 and now it switches the the working tab but all I get is a blank screen, and when I switch over to the logs tab I see that it created a log, but that log is empty.
Also, I'd rather not leave those directories on 777 if I can avoid it.
I am running the latest releases of both BackWPup and WordPress.