IIS Client Certificate Mapping Authentication - mapping not working

I am trying to setup IIS Client Certificate Mapping Authentication and so far I have been unsuccessful.

1. I have a valid client authentication certificate
2. I disabled all authentication methods in the Authentication feature of IIS for the target website
3. Using the configuration editor I setup iisClientCertificateMappingAuthentication as documented in various sources. In this series of screen we map a domain account to a certificate. This is done by exporting the certificate to a text file, removing the first and last line and making sure all is in one line.

The problem is as follows:

When I try browsing to a test page, browser correctly prompts for selection of a certificate. I select the correct certificate. I then get presented with

HTTP Error 401.2 - Unauthorized You are not authorized to view this page due to invalid authentication headers.

If I enable Anonymous Authentication then it works, but the user is not the one in the mapping it is the user running the browser. I know this because the test page contains the following:

response.write (request.servervariables("LOGON_USER")) response.write (request.servervariables("AUTH_USER"))

So the questions are:

1. For IIS Client Certificate Mapping Authentication, is this the only authentication feature that needs to be enabled?
2. Do we need to use the Authorisation feature to limit the users to the one provided in the mapping?

What I am trying to achieve is that only clients that have the certificate will be able to access the service.

What am I missing?

Cheers

Jose