Grouping when create report dynamically

[Slava]

Hi. I try to use this example for create dynamically generated report. I'm want grouping output as described here.Only one change in code from documentation it change

group1.Groupings.Add(new Telerik.Reporting.Grouping("=Fields.ProductID"));

to

group1.Groupings.Add(new Telerik.Reporting.Grouping("=Fields.ProductID"));

 

As I understood this allow me output row with col1=1 in separate group with footer and header,  col1=2 in separate group with footer and header, and two col1=4 with separate group. But it not work as expected. I see one header, one footer and all data between this header and footer.
What I do wrong?
Thank you in advance.

[Slava]

Oh sorry. Of course change to

group1.Groupings.Add(new Telerik.Reporting.Grouping("=Fields.col1"));