Thread:Extension talk:Widgets/"" is not a valid magic thingie for widget

In one of my 1.16.4 MWs the extension "Widgets" (0.9.2, Version 80102) does not work: the wiki page simply renders the source text: . I have checked so far The apache error-log has an entry:
 * the inclusion of the extension "Widgets" (o.k.)
 * the listing of "widgets" as a parser function on Special:Version (o.k.)
 * the permissions of the folder compiled_templates (writable for the server)
 * the existence of the namespace "Widget" and the page "Widget:Google Gadget" with content (o.k.)

Does anybody have an idea why the parser tag is not recognized and how the problem can be solved?

Thank you very much