Error processing Domain Registration

[Webmatic_AUS]

1. I have WHMCS all setup to sell domains. My reseller API is Dreamscape Networks (aka Crazy Domains, Australia)
2. I've done the required things for domain setup and pricing in WHMCS 

WHMCS >> Setup >> Products/Services >> Domain Registrars
WHMCS >> Setup >> Products/Services >> Domain Pricing

My site just went live. So I just tried a demo domain registration (as a "LIVE" test). 

(NOTE: Already verified that my Domain Registrar API is functioning OK: it checked for domain availability,  new customer accounts created in WHMCS are showing up automatically in my Domain Reseller account. So all good so far). 
WHMCS accepted the order for the new domain. I paid and the payment gateway functioned as expected.

But! The domain registration did not process on my Domain Reseller Account. The data never got processed.
It seems to be sitting only in WHMCS... I can't get the domain to try and register on my Domain Reseller. WHMCS is giving an error
"Registrar Error
testdomainame.com.au does not belong to this reseller"
What does this even mean? 

I've now tried a few times and cannot see any way to get this to work?     I can see that the orders are 'active' but they are not working.
I noticed in my WHMCS admin when looking at the 'customer order' area that there was a dropdown for REGISTRAR and I selected 'Dreamscape' it was DEFAULT on "None"

Q: did that cause the problem, and now how do I get the order to process (and ensure it's always  preselected on 'Dreamscape" registrar?) 
My IP is banned from WHMCS - could that be causing the error I wonder? (and the reason I cannot ask for help from WHMCS).

Hoping someone can assist me here! Thank you