C# WPF DataGrid Converters

I've been trying to format fields in a datagrid for days now. How can I simply change the Period is a date field from access. In this attempt I keep getting the error: '{local:DateConverter}' value is not a valid MarkupExtension expression. Cannot resolve 'DateConverter' in namespace 'clr-namespace:Yabba'. 'DateConverter' must be a subclass of MarkupExtension. However the examples I was working from all show DateConverter : IValueConverter. I'm pretty much just want to change the column to list whatever I want based on the date. But can't get any 1 example/method to work. XAML ``` <Window Name="MainForm" x:Class="Yabba.MainWindow" xmlns:local="clr-namespace:Yabba" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="MainWindow" Height="655.217" Width="887.851" Loaded="Window_Loaded"> <Window.Resources> <local:DateConverter x:Key="dateConverter"/> </Window.Resources> <Grid> <DataGrid Name="dataGrid1" AutoGenerateColumns="False" PreviewKeyDown="dataGrid1_KeyDown" CanUserAddRows="false" SelectionUnit="FullRow" IsReadOnly="True" SelectionMode="Single" HorizontalAlignment="Left" VerticalAlignment="Top" Height="348" Width="753" SelectionChanged="dataGrid1_SelectionChanged" Margin="0,20,0,0" MouseDoubleClick="dataGrid1_MouseDoubleClick"> <DataGrid.Columns> <DataGridTextColumn Header="Question" Binding="{Binding title}"></DataGridTextColumn> <DataGridTextColumn Header="Period" Binding="{Binding started, Converter={local:DateConverter}}"></DataGridTextColumn> </DataGrid.Columns> </DataGrid> </Grid> ``` Code ``` namespace Yabba { /// <summary> [ValueConversion(typeof(DateTime), typeof(String))] public class DateConverter : IValueConverter { public object Convert(object value, Type targetType, object parameter, CultureInfo culture) { DateTime date = (DateTime)value; return date.ToShortDateString(); } public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture) { string strValue = value as string; DateTime resultDateTime; if (DateTime.TryParse(strValue, out resultDateTime)) { return resultDateTime; } return DependencyProperty.UnsetValue; } } ``` What am I doing wrong here? Added notes to anyone using this as an example: (Unrelated to question, view selected answer for answer) You may need to change the types depending. ``` [ValueConversion(typeof(DateTime), typeof(String))] ``` I had to change mine to ``` [ValueConversion(typeof(String), typeof(String))] ``` Then recast to DateTime ``` DateTime date = DateTime.Parse((string)value); ```