Enom Reseller For Domain mapping on Pro Sites Created an Error on testing - How to fix?

Hey Super crew,

So basically I'm testing out the Domain mapping Enom Reseller API so my customers can buy their own domain through the site they just setup with pro Sites. Awesome in Theory but for some reason we just tested it out on one of my beta testers and it failed and brought up an Error:

User Defined Extended attribute: registered_for is required for registered_for

This was in the Error log for the reseller API logs. When I viewed the details this is what came up.

{"Command":"PURCHASE","APIType":"API","Language":"eng","ErrCount":"1","errors":{"Err1":"User Defined Extended attribute: registered_for is required for registered_for"},"ResponseCount":"1","responses":{"response":{"ResponseNumber":"301289","ResponseString":"Validation error; missing; extended attribute"}},"MinPeriod":"1","MaxPeriod":"10","Server":"SJL01WRESELL15","Site":{},"IsLockable":"False","IsRealTimeTLD":"True","TimeDifference":"+00.00","ExecTime":"0.270","Done":"true","RequestDateTime":"7\/6\/2014 12:56:30 PM","debug":{}}

thank you so much for any assistance you can offer here. I'm kinda not to sure how to tackle this. My beta tester needed to register the domain ASAP so they went to another provider. Would be so wonderful to have this element nailed as looking to expand this out locally for many people who are already on a waiting list!

Thanks again, just to say what you guys do for Wordpress developers and Designers is totally epic! Makes my life easier and my clients go "Ooooooh".
Jamie