How do I combine multiple subject areas in a one report?

I am a Fusion Financial Customer and I am trying to write a simple report connecting Invoices to Payments. I need to include in my report the AP Routing and the Payment Date. AP Routing only seems to reside in the Payables Invoice - Transaction Real Time subject area and the Payment Date resides in the Payables Payments-Disbursement Real Time subject area. I have a report that is pointing to both of those subject areas BUT if I pull in both fields at the same time, I lose all of my data. If I have them