jQuery.Gantt taskbar not positioned correctly

[clausowitz]

I am using the jQuery.Gantt code on our SharePoint page. I checked all the dates that provide input for the graphical display of the tasks on the Gantt and they are correct. Still the taskbar is not corresponding with the start and end date. All bars end approx. 2 months after the end date as taken from the data.

                $.each(data.d.results, function (i, item){

                    var stat = item.MijnStatus;
		var tit = item.Title;
                    var start = item.Created.substring(0, 10);
                    var LTIOV = item.LTIOV.substring(0, 10);
		var RFInum = item.RFI_nummer;                        
		var balk_kleur;
		var periode = item.Jaar;
			if (stat !="Completed") {
				var start = parseDate(start,"start");
				var end = parseDate(LTIOV, "end");
				var deadline = parseDate(LTIOV, "LTIOV");
				    if (end <= today.getTime()) {
					balk_kleur = "ganttRed";
				    } else {
				        balk_kleur = "ganttGreen";
					}
				dataObj.push(stat);       // needed for the onItemMouseover
				demoSource.push({
            				name: RFInum,
					desc: deadline,
            				values: [{
                				from: start,
                				to: end,
                				label: tit,
                				customClass: balk_kleur,
					dataObj: stat
            }],
					});
								     }
                                                     })   //$.each

function getFutureDate( days ) {
    var millies = 1000 * 60 * 60 * 24 * days;
    var todaysDate = new Date();
    var futureMillies = todaysDate.getTime() + millies;

    return new Date( futureMillies );
}

function parseDate(input,soort_date) {
if(soort_date == "start") {
	var input = getFutureDate( -30 );
			}
  var str = input.split('-');
  var i = str[2];
  i ++;  
	if(soort_date == "LTIOV") {
	        var date1 = new Date(input);
	        var nDate = date1.getTime() + 86400000;
		var ddate = new Date(nDate);
		sDate = getLocaleShortDateString(ddate);
		console.log("LTIOV" + sDate);
	}
	if(soort_date == "end") {
		var sDate = Date.UTC(str[0], str[1]-1,i);
	} 
	if(soort_date == "start") {
		var sDate = Date.UTC(str[0], str[1],str[2]);
	}
	  return sDate;
			   }
        });

Can anyone explain why the graphical display differs from the data?