Grouping is working fine but not displaying the content

[Subhendu]

I have the following XAML :

<telerik:RadGridView.GroupDescriptors>
<telerik:GroupDescriptor Member="{Binding DataContext.VMData.GroupingData,RelativeSource={RelativeSource  AncestorType={x:Type UserControl}}}"    SortDirection="Ascending" />
</telerik:RadGridView.GroupDescriptors>

As far as grouping is concerned this is working fine but the problem is the group descriptor isn't showing any text. Image attached.

Update:
VMData is composite type  as below:
 

[DataContract]
    public class CompositeType
    {
    string groupingData;
        [DataMember]
        public string GroupingData
        {
            get { return groupingData}
            set { groupingData= value; }
        }
}

In View model :

        private CompositeType _vMData= new CompositeType ();
       public CompositeType VMData
       {
           get
           {
               return _vMData;
           }
           set
           {
               _vMData= = value;
            }
       }

[Pavel Pavlov]

Hello,

Have you tried using the DisplayContent property of the GroupDescriptor ?

Regards,
Pavel Pavlov
Telerik