This usually happens for OS that have a confirmation message when you shutdown the system. Since it is an Orderly shutdown, IPMI will have to wait for the message to count down, and if it takes a long time, IPMI will assume it failed. For example, in Red Hat 6, if you go to the menu and choose shutdown, it will pop up a message asking if you want to shut the system down immediately. It also has a 60 second timer in case you didn't pick any option. IPMI will assume it failed, but if you hit refresh, you can that the system Power status is Down now, that means the system did shutdown.