Can't use AD for Administrator authentication

Hello experts,

Bit of a head scratcher. I've created an AD data source for the purpose of authenticating my admins in the CC. Once I do this and attempt to add an administrator, I don't see any option for using my data source to authenticate the user? I've followed the steps from the admin guide (p 572 for data source, 776 fr adding the ldap admin) but I do not see an option to use the ad source for authentication; it just allows me to add a user with a local password.

I'm assuming I'm missing a step here but I'm not sure what.