javascript - Sencha Touch loading xml data via JsonP

Question

I am trying to load xml data via JsonP in sencha touch and I'm very new to sencha touch.

Here is the code of my view

 Ext.define("test.view.list", {
 extend : 'Ext.navigation.View',

requires:[
    'Ext.dataview.List',
    'Ext.data.proxy.JsonP',
    'Ext.data.reader.Xml',
    'Ext.data.Store'
],

config : {

    items : {
        xtype : 'list',
        itemTpl : '{title}',
        title : 'All_data',

        store: {
            autoLoad: true,
            fields: ['title'],
            proxy: {
                type: 'jsonp',
                url: 'http://www.mydomain.com/data.php',
                callbackKey: 'callback',
                callback: function(data){
                    Alert('123');
                },

                reader: {
                    type: 'xml',
                    rootProperty: 'items',
                    record: 'item'
                }
            }
        }

    },
}});

The server-side php:

<?php
$callback = $_REQUEST['callback'];
$data = 
'<items><item><title>Hello</title></item></items>';

if ($callback) {
    header('Content-Type: text/javascript');
    echo $callback . '(' . $data . ');';
} else {
    header('Content-Type: text/xml');
    echo $data;
}

?>

When i try to start it, i get the following error:

Uncaught SyntaxError: Unexpected token <

What can I do, in oder to make it work?

Thank you for helping me out!