set grid cell bool to checked on select

wxPython Users
1

here is my attempt. it simply doesn't check the grid cell. similar code works just fine so it must be something to do with the cell_select event

events.eventManager.Register(self._OnSelectedCell,wx.grid.EVT_GRID_SELECT_CELL,self)
           def _OnSelectedCell( self, event ):
        self.SetCellValue(event.GetRow(),event.GetCol(),'1')
        event.Skip()
        return