Make converter for columnSpan
===

I would like to dynamic do the columnSpan on the userControl. I created the converter class, but it didn’t work. Would you show me how to do it correctly? Thanks.

The code on my UserControl: 

    <TextBlock  x:Name="txtSumary" Grid.Row="0" Grid.Column="1" Text="{Binding summary}"           
       TextWrapping="Wrap"  Style="{StaticResource PhoneTextAccentStyle}" Grid.ColumnSpan="{Binding isSpan, Converter={StaticResource ColumSpanConverter}}"  />

It is reference on the  UserControl.Resources

    <local:VisibilityConverter x:Key="ColumSpanConverter"/>

There is the Converter Class:

     public class ColumSpanConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {          
            bool isSpan = (bool)value;
            return isSpan ? 2 : 0;
        }

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