How to select gid row selection from another grid row selection event

[Nagaraju]

Hello,

I am facing problem with grid default top row selection
calling from another grid row selection event.

here is my code:

protected void Row_Selction(object sender, AjaxEventArgs e)
{
RowSelectionModel sm = this.RulesGrid.SelectionModel.Primary as RowSelectionModel;
sm.SelectedRows.Add(new SelectedRow(0));

}

I have two grids one is RulesGrid another selectiongrid...I am calling RulesGrid row selection in selectiongrid rowselection event.
but it is not showing grid row selected.

Please help me......