excerpt-include doesn't work with news pages

When trying to include an excerpt from a news page, excerpt-include macro complains that it cannot find the page. For example

{excerpt-include:/2006/12/21/News page name}

The same page address works for links and other purposes, but not with excerpt-include (or include macro).

If there is another way to access excerpts from a news item (like you can with blog-posts macro), we would like to know it. We need it for a custom user macro that replaces blog-posts. Currently we're using $post.excerpt but this results in a bunch of text taken directly from the beginning of the news item.