JSONP request doesn't return data, but same? request works fine in store.

[AntaresDaha]

I am pretty new to the concept of JSON/JSONP so i guess I am just missing something very obvious.
I try to figure out how to invoke a JSONP request to a .php script, which in return should provid me with some simple JSON data.
This is my .php script:

<?php
$callback = $_REQUEST['callback'];
$data = 
'[
    {     "id": 1, 
        "name": "Orankesee", 
        "additional": "abc", 
        "url": "www.url.de", 
        "creator": "Beide" },
    {     "id": 2, 
        "name": "Tanzen gehen", 
        "additional": "abc", 
        "url": "www.url.de", 
        "creator": "Valeska" }, 
]';

if ($callback) {
    header('Content-Type: text/javascript');
    echo $callback . '(' . $data . ');';
} else {
    header('Content-Type: application/x-json');
    echo $data;
}
?>

as you can see, pretty straight forward.

Now if I attach a jsonp store proxy that calls this script, everything seems to work fine, the JSON data gets loaded into my store, which is then displayed correctly in a view.
Here is the code of that proxy:

proxy: {
            type: 'jsonp',
            url: 'http://mydomain.com/hosted/test.php',

            reader: {
                type: 'json'
            }
        }

Now if i try to invoke that .php-Skript on my own, I try something like this:

jsonpTest: function(){
    console.log('jsonpTest started!');
    Ext.util.JSONP.request({
        url: 'http://mydomain.com/hosted/test.php',
        callbackKey: 'callback',
        callback: function (jsonData) {
            console.log('jsonpTest raw:', jsonData);
            console.log('jsonpTest parsed:', Ext.decode(jsonData));
        }
    });
}

This function seems to legitimately call the .php script, but if i debug the returned data (jsonData) all it seems to contain is the value 'true'.
Am I missing a second parameter on the callback function, one that contains the response, while I am just getting returned that the request itself worked or something?

[haduki]

callback:function (success, result, errorType, request)

so your 'jsonData' always be a boolean value.

[AntaresDaha]

I actually tried to look up the (possible) params in the Sencha Docs, here:
http://docs.sencha.com/touch/2-0/#!/...method-request
but there I couldn't find the functions signature. -.-
Where did you look up the functions signature?? I guess I could really use an IDE with auto-completition/suggestions for such scenarios, it saves so much time, but all plugins/IDEs i tried out so far were far from clever/helpful or slowed down the IDE itself tremendously (e.g. the sencha eclipse plugin ).