Report from two transaction tables

[nadms]

I'm kind of new to Access. I need to create a report that require information from 2 transaction tables. Here are my tables.
a) Employee

  Fields: -Employee ID (primary key)
          -Employee Name

c) Transaction1

  Fields: -Date
          -Employee ID
          -Revenue1
          -Revenue2

c) Transaction2

  Fields: -Date
    	  -EmployeeID
   	   -Expenses1
          -Expenses2

The Employee lD is linked to both the Transaction tables.
The first report is "Revenue - Employee within a date range" from Transaction1 table and the report is base on a query. To get the Total Revenue, I have =Sum([Revenue1]+[Revenue2]) in Control Source.

The second report is "Expenses - Employee within a date range" from Transaction2 table and the report is base on a query. The Total Expense is = Sum([Expenses1]+[Expenses2]) in Control Source.

I need another report that is similar to the first report. My form require me to enter the Date From and Date To and Employee Name. There should be a row in the report that allows me to show the Total Expenses figure also within the same date range from Transaction2 table. What I want to do is to minus the Total Expenses from my Total Revenue from Transaction1 to get the Actual Revenue.

I am using my second report as a subreport. My report seems to be able to capture records within the date range from the Transaction2.

I've tried to place a text box to show the Actual Revenue and have the following in the Control Source.
=(Sum([tblTransaction1]![Revenue1]+[tblTransaction1]![Revenue2])) -
(Sum([tblTransaction2]![Expenses1]+[tblTransaction2]![Expenses2]))
It doesn't work. Something seems to be wrong here.

Any ideas would be appreciated.