The customer has ordered a subscriptions from his CP and the subscription is Pending with its hostname set as "not assigned" under
Top > Account Director > Customer Manager > Customers > CUSTOMER_NAME > Subscriptions.
The subscription provisioning order is not completed successfully.
Verify the order status under
Top > Billing Director > Receivable > Documents Top > Configuration Director > Logging and Errors > Action Log
Fix the error and process the order. Refer to "Understanding the Orders Processing" for details on order processing.