Export to GCal from GSheet using Apps Script: Exception: Invalid argument: title

I got an error when try to create an event from GSheet data to GCal using Apps script: Exception: Invalid argument: title

The code i used:

function scheduleEvents() {  var spreadsheet = SpreadsheetApp.getActiveSheet();  // var calendarId = spreadsheet.getRange("").getValue();  var eventCal = CalendarApp.getCalendarById("____");  var workplans = spreadsheet.getRange("GE!F14:G16").getValues();  for (x=0; x<workplans.length; x++) {    var event = workplans[x];    var startTime = new Date(event[0]);    var endTime = new Date(event[1]);    var tasks = event[2];    eventCal.createEvent(tasks, startTime, endTime);  }}

Any suggestions ?