[Zope] calling zpt from a script with options

Hi forgive me if it's trivial, but I'm a complete zope newbie.... I read in the zope book that if I want to call zpt from a script (in my case, to render errors in a form) I do something like this: -- script: pt = context.body_content s = pt(zerror="This is an error") return s zpt: <i tal:content="options/zerror | default">error</i> -- This works without a problem, but it only shows the "body_content" file. this file is part of a layout (inside a folder) and I want to call the folder as the url, so it will acquire the index_html in an upper directory. I tried changing the "pt" variable to context.index_html and calling "here/index_html/options/zerror" in the template but it didn't show. how can I achieve that? thanx -- Haim