jsf 1.2 rerendring ui tag generates div tag

I've got the following piece of jsf 1.2 and richface 3.3.3

<s:div id="tree_nav" styleClass="unit size4of5">
        <ul id="ul">
                    <li>< <a:form>
                        <a:commandLink value="test" reRender="tree_nav"
                            action="#{me开发者_如何学PythonnuItemHome.setMenuValue(ldcMenu.id)}" />
                    </a:form> 

                    </li
    </ul>

when the page is first loaded it generates this html:

<div id="main_nav" class="line">
<div id="tree_nav" class="unit size4of5">
<ul id="ul">
<span id="menu:0:j_id36">
<li>

when i do a rerender it generates the following:

<div id="main_nav" class="line">
<div id="tree_nav" class="unit size4of5">
<div id="ul" style="margin-left: 2em">
<span id="menu:0:j_id36">
<li>

Anyonne know why it genereates a div instead of ul after a rerender?

---

Maybe its because you are using s:decorate or include or something similar that renders a div.