I have a Windows Small Business Server 2008 Standard which refuses to configure its backup. I'm using the SBS Console and running through the Wizard which sees and formats the drives and appears to complete successfully. However, after the wizard has finished the SBS console is showing that the backup isn't configured. Looking in the Event Logs I can't see anything which is flagging up, in fact, as far as the event logs are concerned, "A scheduled backup task has been configured on this machine."
Turns out this was the Shadow Copy service that had decided it was going to flake out on us despite showing as running in services.msc and having no errors about it in Event Viewer. A restart and a re-configure of the backups got it running.