Project Invoice Preparation not preparing invoice's

Hi Guys, I’m using the Fixed Fee Billing in Project Entry so I can capture Retainage, otherwise I would skip Project Entry and Keep using deposit invoices, But anyways I’m setting up the Fixed Fee and running the Project Invoice Prep Process but nothing is populating in the Fixed Fee Review. What am I missing? Do I also need to set up a WBS Phase? I’m not receiving any error’s.