[Zope] Simple dtml-unless problem

I have the following code in my standard_html_header <dtml-unless "id == 'index_html'"> <img src="<dtml-var path>/images/transparent.gif" width=400 height=12 alt=""> <H1 align="center"><dtml-var title></h1> </dtml-unless> The problem is, it displays the <img> and <h1> stuff even when the page that the standard_html_header is being dropped into is index_html. I'm pretty sure I'm missing something really silly here, but if anyone could point it out, I'd really appreciate it. cheers tim