Thank you for writing.
The grouping functionality of RadGridView and its ability to build hierarchy are semantically different tasks. While grouping allows you to group any kind of data using different parameters, constructing a hierarchy requires hierarchical data.
Since you mentioned that you could not set up the groups, I would like to point out that there are several articles about RadGridView's grouping functionality in our online documentation: http://www.telerik.com/help/winforms/gridview-grouping-basic-grouping.html
. Some of them might contain the information you need. Additionally, I have prepared a sample project that demonstrates how to use basic grouping.
RadGridView can construct a hierarchy regardless of the type of the data. The only condition is that the data should be hierarchical. The attached project contains a form that illustrates how to build hierarchy using two Lists of business objects.
I hope you will find my answer helpful. Feel free to write back if you need further assistance.
the Telerik team