Hi Disha,
This seems to be more of an attachment problem, Generally when you click on the link the files start downloading from the server, In the above case the file is unavailable in the server to fetch, the URL seems to be ok " WWW " doesn't affect in calling the url.
So please check on attaching the document's / check in the documents correctly part, and when the documents are attached here only the namespace exists but the physical documents failed to be stored in the server hence not able to be retrieved.
Please let me know the process your attaching the files may be I can help on that.
Thanks,
Rabi