New User Creation Policy

Hi I am trying to create a new policy, with following requirements.

UPN = prefix_firstname.lastname

samccountname = UPN

Name (CN) = UPN

however, on creation of the user it errors . . .

• Corporate policy violation. The 'name' property value does not conform to corporate policy. The specified value 'TemporaryCN{9BDAA21D3A5D4e5297F6CFA5E15D7F75}' does not conform to policy requirements.

Thanks in advance.

M