BeginInsert does not seem to be working

[Tarun]

I am setting the itemsource of my radgridview using the code
WireInstructionDGV.ItemsSource = obj.GetWireInstruction("BNYBD", "MST", "CPTY", "USD")

To add a new row, i have a button who's click event has
Me.WireInstructionDGV.BeginInsert()

Clicking on the button does not add a new row in the datagrid. any ideas ?

(I do not have IsReadOnly = True or CanUserInsertRows  = False)

[Tarun]

I figured it out. Instead of making the itemsource a list, i needed to make it an ObservableCollection