Connected to Ax AOS by code

public Axapta Logon()
{
     // NameValueCollection settings = (NameValueCollection)System.Configuration.ConfigurationSettings.GetConfig("AXConnection ");
     string username = System.Configuration.ConfigurationSettings.AppSettings["UserName"].ToString();
     string password = System.Configuration.ConfigurationSettings.AppSettings["PassWord"].ToString();
     string domain = System.Configuration.ConfigurationSettings.AppSettings["Domain"].ToString();
     string defaultCompany = System.Configuration.ConfigurationSettings.AppSettings["DefaultCompany"].ToString();
     string defaultLanguage = System.Configuration.ConfigurationSettings.AppSettings["DefaultLanguage"].ToString();
     string instance = System.Configuration.ConfigurationSettings.AppSettings["Instance"].ToString();// 'DynamicsAxStd@AX4.0:2712'
     Axapta Ax = new Axapta();
     Ax.Refresh();
     NetworkCredential netCredential = new NetworkCredential(username,password,domain);
     Ax.LogonAs(username, domain, netCredential, defaultCompany, defaultLanguage, instance,null);
            
     return Ax;
}