I had this same problem. The problem seemed to be a difference in price between my WHMCS domain pricing and the pricing I had setup through my resellers account.
Hope this helps.
JMT
Is there a way to have multiple database users in WHMCS. I would like the admin section to be able to use a different database user that is set up with different privileges, than the client web side. Is this possible?
Thanks
JMT