Android date time picker open 2 time picker

i used date time picker to get date and time.but its open time picker 2 time.first open date picker.after clicking 'Done' open time picker and again open Time picker.How can i fix this. ??

var picker = Ti.UI.createPicker();
 
                    picker.showDatePickerDialog({
                    callback : function(e) {
                        if (e.cancel) {
                            Ti.API.info('user canceled dialog');
                        } else {
                            start_pick_date = e.value;
                            picker.showTimePickerDialog({
                            //Ti.API.info('user selected date: ' + e.value);
                            //get time value
                            callback : function(e) {
                                var d = new Date(e.value);
                                var hour = d.getHours();
                                var min = d.getMinutes();
                                //start_pick = e.value;
                                var amPM = '';
                                if (hour < 12) {
                                    amPM = 'AM';
                                } else {
                                    amPM = 'PM';
                                }
                                if (hour == 0) {
                                    hour = 12;
                                }
                                if (hour > 12) {
                                    hour = hour - 12;
                                }
 
                                start.value = hour + ' : ' + min + ' : ' + amPM;
                                }
                            });
                        }
 
                    }
                });