[Samba] Lowest functional level 2000 (4.6.4)

[Danny Tipple]

I have a samba dc which i recently upgraded  to 4.6.4.  I was looking at updating the functional level as it currently returns:

Forest function level: (Windows) 2000
Domain function level: (Windows) 2000
Lowest function level of a DC: (Windows) 2000

There is only a single DC (this host).

According to the documentation 2000 isn’t even supported anymore: https://wiki.samba.org/index.php/Raising_the_Functional_Levels
 <https://wiki.samba.org/index.php/Raising_the_Functional_Levels>

 <https://wiki.samba.org/index.php/Raising_the_Functional_Levels>
Any attempt to raise the level with samba-tool returns: 

Domain function level can't be higher than the lowest function level of a DC!

The fsmo roles are as follows:

SchemaMasterRole owner: CN=NTDS Settings,CN=MY-SERVER,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=MyCompany,DC=local
InfrastructureMasterRole owner: CN=NTDS Settings,CN=MY-SERVER,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=MyCompany,DC=local
RidAllocationMasterRole owner: CN=NTDS Settings,CN=MY-SERVER,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=MyCompany,DC=local
PdcEmulationMasterRole owner: CN=NTDS Settings,CN=MY-SERVER,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=MyCompany,DC=local
DomainNamingMasterRole owner: CN=NTDS Settings,CN=MY-SERVER,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=MyCompany,DC=local
DomainDnsZonesMasterRole: * The 'domaindns' role is not present in this domain
ForestDnsZonesMasterRole: * The 'forestdns' role is not present in this domain

Do i need to downgrade samba in order to ‘upgrade’ past 2000?  Was support/raising from 2000 removed at some point?