I would check your configuration, make sure that in the web.config is configured to handle all requests, if this isn't set up it may not be able to render the attachments.
Check that first, if that IS there, next i would post in here an example of the link that is being generated on the page that is not working, perhaps it's the format?
Also is this a single site instance or is it a multiple site instance, as it often requires some extra work to pull in a page attachment from a page on another site onto a different site (often need to manually or programatically add the sitename to the url)