createHTTPClient onload code not collected in time

Hi, I'm porting an iPad project from Titanium 2.X to Titanium 3.X It worked perfectly well in Titanium 2.X

I'm stuck with createHTTPClient. In the dozen JSON calls I make, I get the returned data in onload, and handle it in sometimes complex code. However if the call takes to long I get an undefined object crash.

The main instance is as follows:

var shiftStopSend = Ti.Network.createHTTPClient({
     // function called when the response data is available
     onload : function() {
        response = JSON.parse(this.responseText);   
        success = response.success; // this is where it OFTEN crashes with undefined object
        if(success === 1) {
        // display finish time
        labelNow.text = response.returnTime;
        labelCurr.text = "Finish Time";
 
        } else {
            alert("Action failed. Please contact the administrator.");      
        }   
 
        hideLoader(currWindow.nav);
        currWindow.close(); 
     },
     // function called when an error occurs, including a timeout
     onerror : function(e) {
         var alertDialog = Titanium.UI.createAlertDialog({
            title: 'Network issue',
            message: 'The server could not be accessed',
            buttonNames: ['OK']
            });
        alertDialog.show();
        hideLoader(currWindow.nav);
     },
     timeout : 5000  // in milliseconds
 });
 
 
var dialog2 = Ti.UI.createAlertDialog({
    cancel: 1,
    buttonNames: ['Confirm', 'Cancel'],
    message: 'Are you sure you want to finish the run?',
    title: 'Finish'
 });
 
finishButt.addEventListener('click', function(e) {
      dialog2.show();
});
 
 
dialog2.addEventListener('click', function(e) {
 
    if (e.index===0){ // clicked ok not cancel
        addLoader(currWindow.nav);
 
        if (Ti.Geolocation.locationServicesEnabled) {
            Ti.API.info("in Geo");
                Ti.Geolocation.purpose = 'Get Current Location';
                Ti.Geolocation.accuracy = Ti.Geolocation.ACCURACY_BEST;
                Ti.Geolocation.distanceFilter = 10; 
                Ti.Geolocation.preferredProvider = Ti.Geolocation.PROVIDER_GPS;
 
                 Ti.Geolocation.addEventListener('location', function(e) {
 
                    if(e.error) {
                          alert('Error: ' + e.error);
                    }
                    else {
                        Ti.API.info(e.coords);
                        var latitude = e.coords.latitude;
                        var longitude = e.coords.longitude;
 
                        //open login web service
                        shiftStopSend.open("POST", siteRoot + "mylink.php");
 
                        var ids = selectedShifts.join(";");
                        var params = {
                            action: "finish",
                            comment: " ",
                            latitude_finish: latitude,
                            longitude_finish: longitude,
                            ids : ids
                        };
                        shiftStopSend.send(params);     
                    }//else
 
                });
 
 
        }else{
            alert('Please enable location services');   
        }
 
     }

I've read about callback functions but I'm a bit surprised, surely it must be possible to use the onLoad? How would you handle that?