<UserControl x:Class="SLGridImage.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    d:DesignHeight="300" d:DesignWidth="400" xmlns:sdk="http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk">

    <UserControl.Resources>
        <local:LevelToVisibilityConverter x:Key="LevelToVisibility" />
    </UserControl.Resources>


    <Grid x:Name="LayoutRoot" Background="White">
        <sdk:DataGrid x:Name="dgMarks"  CanUserResizeColumns="False"  SelectionMode="Single" 
               AutoGenerateColumns="False" 
                      VerticalAlignment="Top" 
                      ItemsSource="{Binding MarkCollection}"
                      IsReadOnly="True"  
                      Margin="13,44,0,0" 
                      RowDetailsVisibilityMode="Collapsed" Height="391" 
                      HorizontalAlignment="Left" Width="965" 
                      VerticalScrollBarVisibility="Visible" >
            <sdk:DataGrid.Columns>
                <sdk:DataGridTemplateColumn>
                    <sdk:DataGridTemplateColumn.CellTemplate>
                        <DataTemplate>
                            <Button x:Name="myButton"   
                            Click="myButton_Click">
                                <StackPanel Orientation="Horizontal">
                                    <Image Margin="2, 2, 2, 2"  x:Name="imgMarks"  Stretch="Fill" Width="12" Height="12" 
                                           Source="Images/test.png"
                                           VerticalAlignment="Center"
                                           HorizontalAlignment="Center"
                                        Visibility="{Binding Level, Converter={StaticResource LevelToVisibility}}"
                                     />
                                    <TextBlock Text="{Binding Level}" TextWrapping="NoWrap"  ></TextBlock>

                                </StackPanel>
                            </Button>
                        </DataTemplate>
                    </sdk:DataGridTemplateColumn.CellTemplate>
                </sdk:DataGridTemplateColumn>
                <sdk:DataGridTemplateColumn  Header="Name" >
                    <sdk:DataGridTemplateColumn.CellTemplate>
                        <DataTemplate >
                            <Border>
                                <TextBlock Text="{Binding Name}" />
                            </Border>
                        </DataTemplate>
                    </sdk:DataGridTemplateColumn.CellTemplate>
                </sdk:DataGridTemplateColumn>

                <sdk:DataGridTemplateColumn  Header="Marks" Width="80">
                    <sdk:DataGridTemplateColumn.CellTemplate>
                        <DataTemplate>
                            <Border>
                                <TextBlock Text="{Binding Marks}" />
                            </Border>
                        </DataTemplate>
                    </sdk:DataGridTemplateColumn.CellTemplate>
                </sdk:DataGridTemplateColumn>
            </sdk:DataGrid.Columns>
        </sdk:DataGrid>
    </Grid>
</UserControl>

in .cs

using System; using System.Collections.Generic; using System.Linq; using System.Net; using System.Windows; using System.Windows.Controls; using System.Windows.Documents; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Animation; using System.Windows.Shapes; using System.Collections.ObjectModel; using System.ComponentModel;

namespace SLGridImage { public partial class MainPage : UserControl { private MarksViewModel model = new MarksViewModel(); public MainPage() { InitializeComponent(); this.DataContext = model;

    }

    private void myButton_Click(object sender, RoutedEventArgs e)
    {

    }



}

public class MarksViewModel : INotifyPropertyChanged
{

    public MarksViewModel()
    {

        markCollection.Add(new Mark() { Name = "ABC", Marks = 23, Level = 0 });
        markCollection.Add(new Mark() { Name = "XYZ", Marks = 67, Level = 1 });
        markCollection.Add(new Mark() { Name = "YU", Marks = 56, Level = 0 });
        markCollection.Add(new Mark() { Name = "AAA", Marks = 89, Level = 1 });

    }


    private ObservableCollection<Mark> markCollection = new ObservableCollection<Mark>();
    public ObservableCollection<Mark> MarkCollection
    {
        get { return this.markCollection; }
        set
        {
            this.markCollection = value;
            OnPropertyChanged("MarkCollection");
        }
    }


    public event PropertyChangedEventHandler PropertyChanged;

    public void OnPropertyChanged(string propName)
    {
        if (PropertyChanged != null)
            this.PropertyChanged(this, new PropertyChangedEventArgs(propName));
    }

}

public class Mark
{
    public string Name { get; set; }
    public int Marks { get; set; }
    public int Level { get; set; }
}

public class LevelToVisibilityConverter : System.Windows.Data.IValueConverter
{
    #region IValueConverter Members

    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        Visibility isVisible = Visibility.Collapsed;
        if ((value == null))
            return isVisible;
        int condition = (int)value;
        isVisible = condition == 1 ? Visibility.Visible : Visibility.Collapsed;
        return isVisible;
    }

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

    #endregion
}

}

when i run getting error

The type 'local:LevelToVisibilityConverter' was not found. Verify that you are not missing an assembly reference and that all referenced assemblies have been built.

what i am i missing here looking forward for an solution thank you