JSONP not working

Question

I am making a jQuery Mobile and PhoneGap app. I need to submit a form. I made something like this:

$.ajax(
                {
                url: 'http://ip.ip.ip.ip:8070/services/rest/operator/login',//?email=' + email + '&password=' + haslo,
                dataType: 'jsonp',
                type: 'GET',
                callback: 'jsonpCallback',
                jsonpCallback: 'jsonpCallback',
                jsonp: '_jsonp',
                data: ({'email' : email, 'password' : pass}),
                contentType: 'application/x-www-form-urlencoded',

                success: function (data) {
                    window.location = ('file:///android_asset/www/custom/main.html');
                },

                error: function (data) {
                    alert('Login i/lub hasło nieprawidłowe '+data);
                }
            });

It works on Chrome but doesn't on my Android device. I read the documentation of both PhoneGap and jQuery Mobile, and I tried whitelisting, $.mobile.allowCrossDomainPages and $.support.cors. As I know that PhoneGap allows cross-domain I also tried to change datatype to json.

Unfortunately I have no access to server-side code. I just have this short "wadl". Web service returns 200 success or 401 access denied.

<resource path="/operator">
     <resource path="/login">
          <method name="GET">
                <request>
                     <representation mediaType="application/x-www-form-urlencoded">
                          <param name="email" style="query" type="xs:string"/>
                          <param name="password" style="query" type="xs:string"/>
                     </representation>
                </request>
                <response>
                     <representation mediaType="application/octet-stream"/>
                </response>

What am I missing?

Note: Only once I received [object Object] error message. But I have no idea how:)

Answer 1

Quentin was right. It was a server-side problem. When using JSONP reqests, server has to provide a response in json format, not only status code. It was enough to add true and false (properly json formatted) as a response.