CurrentRowChanged does not work as intended?

[Edward]

I have a grid like

Master 1
- Child 1
- Child 2
Master 2
- Child 3
- Child 4

If I select Child 1,then Master 2, CurrentRowChanged fired.

However,if I select Child 1 again, CurrentRowChanged didn't fire.

If I click between Child 1 and Master 2, then nothing happens.

Is there any other event handler I can use?

I tried

CurrentRowChanged
CurrentCellChanged
SelectionChanged