I wish to use a TextBlock for display of a data column header.

This seems straightforward...

                    <telerik:GridViewDataColumn ColumnGroupName ="Group1" DataMemberBinding="{Binding ColumnOneBinding}" >
                        <telerik:GridViewDataColumn.Header>
                            <TextBlock Text="Hello" />
                        </telerik:GridViewDataColumn.Header>
                    </telerik:GridViewDataColumn>

...however, instead of displaying 'Hello' as would be expected. The display (in both design and runtime), is 'System.Windows.Controls.TextBlock'

If this is due to an older version of the Telerik controls, is there any fix, or is the only option to purchase the new controls?