average value does not display in openoffice.org base report

I have a database created in Openoffice.org Base version 3.2. I do NOT have Sun Report Builder extension installed. The database has records with fields: Date, Reading 1,...,Reading 4.I create a report displaying the database records. In the design mode of the report, I add a numeric field. I right-click on the field, select Form...Data tab type SQL command, with content SELECT Average("Reading 1") as "Avg1" from "Blood Sugars". When I open the report, the average does not display. The box surrounding the field displays. When I replace Average with Count, or Sum, or most other functions, the indicated result displays with no problem. Am I doing something wrong or is there a bug?
Thanks,
Joe