function isClosedColumnChanged(e)
{
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var sheet = ss.getActiveSheet();
  //Get Active cell
  var mycell = ss.getActiveSelection();
  var cellrow = mycell.getRow();
  var isClosed = 'K' + (cellrow);

  if (cellcol == 11)
  {

    if (sheet.getRange(isClosed).getValue() == "closed")
    {
      messageit('its forbidden to close already-closed call');
    }
  }
}