无法转换到事件处理KeyPressEventHandler

Question

虽然运行下面的代码，我得到这个异常：

无法隐式转换System.Eventhandler到 System.Window.Form.KeyPressEventHandler

private void grdPOItems_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e) 
    { 
     int colIndex = grdPOItems.CurrentCell.ColumnIndex; 
     string colName = grdPOItems.Columns[colIndex].Name; 
     if(colName == "Qty" || colName == "Rate") 
     { 
      e.Control.KeyPress += new EventHandler(CheckKey); 
     } 
    } 

    private void CheckKey(object sender, EventArgs e) 
    { 
     if (((e.KeyChar < 48 || e.KeyChar > 57) && e.KeyChar != 8 && e.KeyChar!='.')) 
     { 
      e.Handled = true; 
     } 
    }