無法轉換到事件處理KeyPressEventHandler

Question

雖然運行下面的代碼，我得到這個異常：

無法隱式轉換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; 
     } 
    }