Why can I not authenticate with users on a Windows 2008 system in an IdM domain?

Issue

• I am trying to use a Windows 2008 system in a Red Hat Identity Management (IdM) domain to authenticate users. I do not succeed to authenticate at the Windows login prompt, althou used the user credentials are verified to work on other systems in the IdM domain. The errormessage saye wrong username or password.
• On the IdM server I see the following error when the userlogin is attempted:

ipa.example.org krb5kdc[4242](info): AS_REQ (6 etypes {18 17 23 24 -135 3}) 10.0.0.2: CLIENT_NOT_FOUND: test@example.org for krbtgt/example.org@example.org, Client not found in Kerberos database