SelectOneMenu from one extra entry the value is set to null

[jones.kong83.gmail.com]

I have a list of categories and want to add one not existing category (an all category).

<h:selectOneMenu value="#{categoryBean.selectedCategory}">
<f:selectItems value="#{categoryBean.categorySelectItems}"/>
<s:convertEntity />
</h:selectOneMenu>

private Shelf allCategory = new Category(1);

public List<SelectItem> getCategorySelectItems() {
          List<SelectItem> items = new ArrayList<SelectItem>();          
          items.add(new SelectItem(allCategory, "search All"));
          for (Category cat : getCategories()) {
               items.add(new SelectItem(cat, cat.getName()));
          }
          return items;
     }

For every item except the newly added allCategory i get the right object, just when i select search All i get a null instead of the object in setSelectedCategory(). And return items; contains at the zero index the allCategory object like it should. And the POST is transmitting the 0 as index (like it would 2 or 3 for the other selectItems)