Problem with form inside div

I have the following snippet of code in my tml file:

<div id="categorypopup_div_${headline.id}" class="popup long">
      
     <form t:id="categoryform">
       <input type="hidden" name="headlineId" id="headlineId" value="$
{headline.id}"/>
       <select t:id="category"
               t:type="select"
               t:model="allCategoriesModel"
               t:encoder="allCategoriesModel"
               t:blankOption="ALWAYS"
               t:blankLabel="Choose new cat"/>
       <br/><br/>
       <input type="submit" id="save" value="Save"  
class="popup_closebox"/>   
       <span class="popup_link popup_closebox">Cancel</span>
     </form>
</div>

When the page is accessed via Firefox (with Firebug), it is rendered as:

<div... />
<form>
....
</form>

where the form is outside of the <div>...

Any ideas?  I am very new to Tapestry development...

Thanks,
Andrew