ultra explorer bar throws exception "Object reference not set to an instance of an object" when drag and drop any group to any other control (like drag the ultra explorer bar and drop to the win form header)

i have tried all this but to no avail

            this.ultraExplorerBar1.GroupSettings.AllowDrag = DefaultableBoolean.False;
            this.ultraExplorerBar1.ItemSettings.AllowDragCopy = Infragistics.Win.UltraWinExplorerBar.ItemDragStyle.None;
            this.ultraExplorerBar1.AllowDrop = false;
            this.ultraExplorerBar1.CausesValidation = false;
            this.ultraExplorerBar1.EventManager.AllEventsEnabled = false;
            this.ultraExplorerBar1.ItemSettings.AllowDragMove = Infragistics.Win.UltraWinExplorerBar.ItemDragStyle.None;
            this.ultraExplorerBar1.ItemSettings.AllowEdit = DefaultableBoolean.False;