If - else statement not working in Android

So I have my class extending AppCompatActivity. On button press I'm creating new Async task for internet connection passing reference to this class, and at the end of doInBackground I call function in my class.

private LoginAct act;

[...]

@Override
protected Object doInBackground(Object[] params) {
    try
    {
        //LOGIN into account or create new one - returns id (as string str)
        int id = Integer.parseInt(str.toString());
        System.out.println(id);
        //id is fine
        act.postexecute(id);
    } catch (Exception e) {
        return "ERROR: " + e.getMessage();
    }
    return null;
}

as for now, everything is fine, but than postexecute method not work as it's suppsed to:

public void postexecute(int id)
{
    //it works fine here
    if(id == 0)
    {
        System.out.println("postexecuting!");
        edPas.setError("Nickname and password don't match!");
        loadBar.setVisibility(View.GONE);
    }
    else
    {
        System.out.println("Less postexecuting!");
        onBackPressed();
    }
}

Problem is, no matter what id input is, neither if or else statements prop. I have no idea, what the problem could be, and all questions I've seen around weren't even close to my problem...