Grouping Information on Data Reports

Can anyone tell me why there is a function on data reports which doesn't work???
I cannot understand it's existence!!!
You can make by your own a self-test:
Create a simple data report (using dataenvironment). Set the data report's datamember property to the command that you have specified on the dataenvironment and then right click on the report and select 'Retrieve Structure'. Then drag & drop all the desired fields on the report. This work well!!!
But the following doesn't:
If you try to right click on the report and select: 'Insert Group Header', then you will get a message: "Data report sections do not match with data source" when you run the program.
Only if you remove this group header the program will work again...
And I am asking, where is based the existence of 'Insert Group Header' while it doesn't work???

Michael Vlastos
Automation Engineer
Company SouthGate Hellas SA
Development Department
Athens, Greece