select the first row in datagridview

Question

when I write this code
GridViewPays.CurrentCell = GridViewPays.Rows[1].Cells[0];
it selects the second row
but when I change indexrow to 0
GridViewPays.CurrentCell = GridViewPays.Rows[0].Cells[0];
it doesn't work
what' the problem? I have number sequence column in same datagridview