Error with loginIn using Skype Web SDK

I try to make web app using Skype Web SDK. And when I try to login in I have this status SigningIn... and that's all.

Then app doing nothing. I can't login in. Why?

This is me code

var Application;
var client;

Skype.initialize({
    apiKey: 'SWX-BUILD-SDK',
}, function(api) {
    Application = api.application;
    client = new Application();

    client.signInManager.state.changed(function(state) {
        $('#state').text(state);
    });

}, function(err) {
    alert('some error occured: ' + err);
});

$('#loginBtn').click(function() {
    client.signInManager.signIn({
        username: $('#username').val(),
        password: $('#password').val()
    }).then(
        function() {
            alert('Sign in as ' + client.personAndGroupsManager.mePerson.displayName());
        }, function(err) {
            alert(err || 'Cannot sign in');
        }
    );
});