Are you downloding with a browser, or with Play Store? If Play Store, it means that something went wrong between the app seeing the address of the app and the server seeing its request for the download.
If you're downloading it manually, it probably means that the site has a bad address for the app. And you shouldn't be downloading apps manually.
Please create a free account here, so that you can answer in the thread, and not have the discussion scattered all over the forum.