I am running about 6 domain controllers. I upgraded them all from server 2003 ent edition to server 2008 ent edition. In AD domain controllers OU when I click on the properties and Operating system of the last DC I upgraded, it still shows as server 2003 hence the domain functional level cannot be upgraded. When I try to raise the domain functional level the error says 'you cannot raise the domain functional level because this domain includes the DCs not running the appropriate version of windows, I click save as on this error and it shows me the name of the last DC I upgraded'.
What can be done? help