I am trying to pass SubscirberID field and set as the SendableDataExtensionField but is not working. The doc for Fuel SDK say you can only use _SubscriberKey or EmailAddress.
I am not using Fuel but assuming it is the same. I want to have a field SubscriberID and relate it to the SubscriberID field on ET.
I saw this post here and I get a similar error "The SendableSubscriberField field cannot be blank.".
I can see it is looking for SubscriberKey in the soap but I do want to use SubscriberID. Any ideas or anyone run into this before?