Basic Authorization Android Distribute Problem

I wrote this code:

    var xhr = Ti.Network.createHTTPClient();
    xhr.onerror = function(e){
        alert(this.status);
    }
    xhr.onload = function(){
        //Titanium.API.info("risposta = " + this.responseText);
    };

    xhr.setValidatesSecureCertificate = false;
    authstr = 'Basic ' + Titanium.Utils.base64encode(textFieldUser.value + ':' + textFieldPass.value);
    xhr.open("POST", 'https//miourl.php');

    xhr.setRequestHeader('Authorization', authstr);
    xhr.setRequestHeader('Content-Type', 'text/xml');

    xhr.send(xmlSendParam);

If I start the emulator or I click on Android Device works correctly. If I click on distribute and I install l'apk on device, authentication fails. I use sdk 2.1.3.GA and I compiled with Android 2.2. What's wrong?