WPF Usercontrol property inaccessible

I have created a simple UC control, which combines two TextBlock and one Textbox.
But when I use this UC,it compains of"not recognized or is not accessible.

Error:
The member "Title" is not recognized or is not accessible.

I use .NET 4.5, VS2012.

Anyone can help? THANKS a LOT!

    public partial class UCComboTextbox : UserControl
    {
        public static DependencyProperty ISDescriptionEnabledProperty = DependencyProperty.Register("ISDescriptionEnabled", typeof(bool), typeof(UCComboTextbox), new PropertyMetadata(false));
        public static readonly DependencyProperty DescriptionVisibilityProperty = DependencyProperty.Register("DescriptionVisibility", typeof(Visibility), typeof(UCComboTextbox), new PropertyMetadata(false));
        public static DependencyProperty TitleProperty = DependencyProperty.Register("Title", typeof(string), typeof(UCComboTextbox), new PropertyMetadata(false));
        public static DependencyProperty DescProperty = DependencyProperty.Register("Desc", typeof(string), typeof(UCComboTextbox), new PropertyMetadata(false));

        public bool ISDescriptionEnabled {get;set;}
        public Visibility DescriptionVisibility
        {
            get
            {
                if (ISDescriptionEnabled)
                    return System.Windows.Visibility.Visible;
                else
                    return System.Windows.Visibility.Collapsed;
            }
        }

        public string Title { get; set; }
        public string Desc { get; set; }

        public UCComboTextbox()
        {
            InitializeComponent();
            DataContext = this;            
        }
    }
}


The xaml that uses this UC:

        <local:UCComboTextbox x:Uid="ServerName" x:Name="ServerName" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="0,30,0,0"
                              Title="{x:Static resx.AddUpdateServerView.ServerNickName}"
                              Desc="{x:Static resx:AddUpdateServerView.ServerNickNameDesc}" />