I've just finished to install Akeebabackup for Wordpress and I get this error:
Service definition is not a Closure or invokable object.
I've read a ticket from a user who had the same problem but you said it was probably because of Wordpress Version.
I have Akeebabackup for Wrodpress in another domain in the same server and I don't have this problem. I've already uninstalled the plugin and reinstall but I always get the same error.
The fist time I've installed the plugin, just after activating it I was presented with a Internal error page and after refreshing it I would get Service definition is not a Closure or invokable object.