Calculating Subsummaries with Functions

Hi, I have a database of patient surveys, which I created in Filemaker Pro 6 and upgraded to Filemaker Pro 7.

When I viewed the new version of the database, I came across a problem apparently caused during the upgrade.  In my Report, some fields are based on the results of calculations from other fields.

For example (Responses are ranked 1 to 5--1 being bad, and 5 being good):

Admission:                Avg. Response
Staff Courtesy            3.0
Delays                       2.0
Total                         2.5

In a Grand Summary Report, the above example works fine in both FM 6 and 7.

In the above example, Total = Average (Staff Courtesy, Delays)

However, I have problems if I use sub-summaries when evaluating Total.

In FM 6, the subsummaries work without problem when calculating Total; in FM 7, however, I get the average for ALL records in the database (i.e. the subsummary is not working).

The formula I am using is:

FM6:
Total = Average(GetSummary(Staff Courtesy, Survey Date), GetSummary(Delays, Survey Date))

FM 7:
Total = Average(GetSummary(Staff Courtesy; Survey Date); GetSummary(Delays; Survey Date))

In each case, the records are sorted according to Survey Date.  


I should also add:  

Subsummaries NOT involving functions DO work in my FM 7 database.

For example, the following formula would work in my subsummary report:
Number of Patients = GetSummary(Patients Group A, Survey Date) + GetSummary(Patients Group B, Survey Date)

My problem seems to happen only when I use functions (such as Average) with parameters requesting a SubSummary.

Is it at ALL possible for me to calculate an Average using subsummaries in FM 7?  Any thoughts or guidance would be MOST appreciated!