Using DragDrop on a datagridview with a bound datatable

PrivateSub InputGrid_DragDrop(ByVal senderAsObject,ByVal eAs System.Windows.Forms.DragEventArgs)Handles InputGrid.DragDrop

Dim controlMousePosAs Point = InputGrid.PointToClient(New Point(e.X, e.Y))

Dim hitTestAs DataGridView.HitTestInfo

Dim ColAsInteger = InputGrid.Columns.Item("Graphic_Id").Index

InputGrid(Col, hitTest.RowIndex).Value = e.Data.GetData(DataFormats.Text)
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The problem is that the row does not get marked as modified in the bound datatables state variable. I can click a cell and enter a number. When I do this the row is marked as modified. Drag and Drops do not even though the datagridview shows the new value.
How is it possible that the DataGridView can show the updated value without changing the bound datatables state to modified?

Is there an update command or do I have to manually force the datatable row to a modified state? Is the value not being written to the datatable at all so it is never marked as modified?

Thanks
JD