Page Comparison

A task needs to be enabled in order for the customer to get Invoiced.
To activate the task go to Administration> Advanced> Tasks> Invoice Pre Ordered Products turn the check box on 'Enabled' and click on Save.
Enter the appropriate value in the Schedule field and to do so see link Setting task schedules.
The task will run based upon the values set on the count cycle selected.

Quantity Invoiced formula for Quantity Invoiced = Unit Quantity\Number of Invoices
Value Invoiced formula = Unit Quantity x Unit price ex tax \ Number of Invoices.

The billing rate is separate to the usage rate and the usage rate has to be the same values as the line that is getting credited.

A product needs to be set up to be used in the credit lines generated by the preordered contract product. See more details below.

In Preordered products on the Used Shipment Lines tab, displays a list of the Usage Shipments Lines and Redemptions when the service is used up.
In Preordered products on the Invoiced shipment lines tab, displays a list of shipments when the customer has been charged for the pre-ordered product.