Category Linked articles with embedded Pdf fails to display

I have an article that is displayed with a category link.

The article has an embed Pdf link

The Pdf does not display (404 error) because the URL embeds the category as part of the link address to the pdf file.

Everything works OK when directly addressing the Pdf or embed dinging a link to it in the article.

What I would like is for the pdf to display when the article is selected from the list of articles by category

Is there a way round this?