Joining Two Reports

Joining Two Reports

Hello Guys,
I have three modules:
- Orders - Custom module
- Clients - Contacts
- Basic Pay

I am using the order module to store the revenue share amount for each order which will be paid a sales rep

The Orders are child or clients so I am pulling a report of clients and grouping the field of sales rep
This is coming very well.

I also have a report which show the basic pay of each Sales Rep
I need to join the basic + Revenue share amount from the report of (Clients + Orders)

When i try to join, it doesn't show me the report for the basic pay

does anyone has an idea of what needs to be done?