Error_1_The type or namespace name 'DateBinding' could not be found (are you missing a using directive or an assembly reference?)

my code works but im getting this error can someone explain what it means. Thanks in advance

------------------------------------------------------------(Xaml)

<Window x:Class="DateBinding.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:loc="clr-namespace:DateBinding"
    Title="Window1" Height="450" Width="300">
    <Window.Resources>
        <loc:DateConverter x:Key="dteConverter"/>
        <loc:DateColorConverter x:Key="DteColConverter"/>
        <BooleanToVisibilityConverter x:Key="boolVisConverter"/>
        <loc:Txt2LenConverter x:Key="txt2lenConverter"/>
        <loc:DayWeekToOpacityConverter x:Key="dwToOpacityConverter"/>
    </Window.Resources>

    <StackPanel>
        <Slider Name="slDate" Maximum="20" SmallChange="1" Margin="3"/>
        <TextBox  Name="txtDate" VerticalAlignment="Top" FontSize="28" Margin="3" Padding="3,0,0,0" Background="{Binding Text, Converter={StaticResource DteColConverter}, ElementName=txtDate, Mode=OneWay}">
            <TextBox.Text>
                <Binding ElementName="slDate" Path="Value" Mode="OneWay" Converter="{StaticResource dteConverter}"/>
            </TextBox.Text>
        </TextBox>
        <CheckBox Name="chkPicture" Content="Check for Photo" IsChecked="True"/>
        <Image Source="Penguins.jpg" Visibility="{Binding ElementName=chkPicture, Path=IsChecked, Converter={StaticResource boolVisConverter}}" 
               Opacity="{Binding Text, ElementName=txtDate, Converter={StaticResource dwToOpacityConverter}}"/>
        <TextBox Name="txtLen" FontSize="30" Text="Initial"/>
        <ProgressBar Height="10" Value="{Binding ElementName=txtLen, Path=Text, Converter={StaticResource txt2lenConverter}}"/>
    </StackPanel>
</Window>

--------------------------------------------------------------(xaml)

-----------------------------------------------------------------(code behind)

namespace DateBinding
{
    /// <summary>
    /// Interaction logic for Window1.xaml
    /// </summary>
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();
        }
    }
}

------------------------------------------------------------(code behind)

-----------------------------------------------------------(date converter)

namespace DateBinding
{
    public class DateConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            DateTime d = DateTime.Now;
            d = d.AddDays((Double)value);
            return d.ToShortDateString();
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }   // end DateConverter

    public class DateColorConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            DateTime d;
            if (!DateTime.TryParse((string)value, out d))

                //return new SolidColorBrush(Colors.WhiteSmoke);
                //return new SolidColorBrush(Color.FromArgb(255, 255, 255, 0));
                return new SolidColorBrush(Colors.Wheat);
            if (d.DayOfWeek == DayOfWeek.Saturday || d.DayOfWeek == DayOfWeek.Sunday)
                return new SolidColorBrush(Color.FromArgb(255, 155, 0, 55));
            return new SolidColorBrush(Colors.Aquamarine);
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }

    public class Txt2LenConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            string str = (string)value;
            return str.Length * 2;
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }

    public class DayWeekToOpacityConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            DateTime d;
            DateTime.TryParse((string)value, out d);
            return (float)d.DayOfWeek / 10;
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }
} 

-------------------------------------------------------------(dateConverter)