Grid Utils SimpleStringConverter

I am havign a problem when using the EditButtonValueRenderer also the Simple String Converter

.setRenderer(new EditButtonValueRenderer(new RendererClickListener() {

            public void click(RendererClickEvent event) {
                // TODO Auto-generated method stub
                System.out.println("Change Privilege" + event.getPropertyId());
        }), new SimpleStringConverter<String>(String.class) {

            public String convertToPresentation(String value, Class<? extends String> targetType, Locale locale)
                    throws {
                // TODO Auto-generated method stub
                return String.format("<b>%s</b>", value);

[/code]The column username is came from GeneratedPropertyContainer which means the username is came from the child value of the main class value
I use JPAContainer to put data on the grid…
when I run the application the grid is on the mess.

how do I solve this?