These sites you are referring to are accessible from the internet. Your intranet (as the name and the error-message suggest) is not.
Facebook can not link anything to the timeline that will not be accessible to other users.
EDIT (add workaround from comments):
You can try this workaround:
Put up a public campaign site that serves every request (no matter what url-params) to a basic main-page with general information and maybe some links. The main-page contains a little javascript that checks if your intranet-page is available from client-side.
- yes: Forward the browser to the intranet-page based on your url-params.
- no: The user sees some basic information about your campaign on the public page.
This way you provide at least some useful information (instead of 404s) to facebook's servers and the linking should work.