xinha editor won't show format block

Sites generated with the archetype have a formatblock ((header drop down etc.)) in their xinha configuration.
But when I open a textarea, with a xinha toolbar, I don't see the format block.

Looking into the html source code, I see the select box [1], but it won't render on my (firefox) browser.

Smells like a javascript issue?

1)
<td class="toolbarElement"><select class="" title="">
<option value="">— format —</option>
<option value="h1">Heading 1</option>
<option value="h2">Heading 2</option>
etc...