Subtracting the sum of one field in a table from the sum of another

I have what I thought would be an easy question, but if it was easy, maybe I wouldn't have the problems that I do. I have a very simplistic database, in MSACCESS right now but will eventually port over to Oracle. In my database I have two tables...one called COST and one called FUNDING. My COST table is a running list of expenditures for individual projects. My FUNDING table is the total funds available for a project. All I want to do is get a sum of all of the cost in the FUNDING table, and subtract the sum of all of the expenditures in the COST table.  The problem is that I'm getting the wrong result. In my FUNDING table I have two entries, PROJ1  with a price of $6,605,000.00 and PROJ2 with a price of $1,000,000.00 for a total of $7,605,000.00. In my COST table I have several projects related to each individual PROJ1 or PROJ2. It appears that the individual project costs for PROJ2 are not being picked up in the query, because my total amount is incorrect by $3.96 which is the exact amount of the sumed costs for PROJ2. So what am I missing here, or misunderstanding?? Any help would be greatly appreciated!!!! (My cose is below) Thanks Alot!!!!

<cfquery name="BalanceTotal" datasource="MCAdb">
    SELECT SUM (COST.DISBURSED) AS Balance,
      SUM(FUNDING.FUNDED_AMOUNT) AS FundingBalance,
      (FundingBalance - Balance) AS TotalBalance      
      FROM FUNDING, COST
      GROUP BY COST.ID      
    </cfquery>Start Free Trial