Converter failed to convert error

Question

I have a BooleanToVisibilityConverter and an InverseBooleanToVisibilityConverter in my silverlight project. Both fairly standard but for some reason in this one dialog they throw lots of errors (at least I think its the Converter). I cannot seem to get it to throw any exceptions I can view I just get this output and I'm not sure why!

System.Windows.Data Error: 'MS.Internal.Data.DynamicValueConverter' converter failed to convert value 'True' (type 'System.String'); BindingExpression: Path='CategoryTitle' DataItem='null' (HashCode=0); target element is 'System.Windows.Controls.Grid' (Name=''); target property is 'Visibility' (type 'System.Windows.Visibility').. System.ArgumentException: Requested value 'True' was not found.
   at System.Enum.EnumResult.SetFailure(ParseFailureKind failure, String failureMessageID, Object failureMessageFormatArgument)
   at System.Enum.TryParseEnum(Type enumType, String value, Boolean ignoreCase, EnumResult& parseResult)
   at System.Enum.Parse(Type enumType, String value, Boolean ignoreCase)
   at MS.Internal.SilverlightTypeConverter.ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, Object value)
   at MS.Internal.Data.DefaultValueConverter.ConvertHelper(Object o, Type destinationType, CultureInfo culture, Boolean isForward)
   at MS.Internal.Data.TargetDefaultValueConverter.Convert(Object o, Type type, Object parameter, CultureInfo culture)
   at MS.Internal.Data.DynamicValueConverter.Convert(Object value, Type targetType, Object parameter, CultureInfo culture)
   at System.Windows.Data.BindingExpression.ConvertValue(Object value, DependencyProperty dp, String failureResource). 

Here is the XAML

<converters:InverseBooleanToVisibilityConverter x:Key="InverseBoolToVisibility" />
<Grid Visibility="{Binding CategoryTitle, Converter={StaticResource InverseBoolToVisibility}, FallbackValue=True}">

The property Im bound to:

public bool CategoryTitle { get; set; }

And the converter itself

public class InverseBooleanToVisibilityConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        return !(bool)value ? Visibility.Visible : Visibility.Collapsed;
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        Visibility vis = (Visibility)value;

        if (vis != Visibility.Visible)
        {
            return true;
        }

        return false;
    }
}

Answer 1

System.ArgumentException: Requested value 'True' was not found.

This is because Visibility expects a Visibility Enum type. You are attempting to use a bool value for this in your FallBackValue.