"An error occurred while reading the federation metadata."
You can often ignore this. I assume your connection is https?
Why do you have a certificate for the fedlet? Are you trying to sign the AuthnResponse?
Look at the ADFS logging - How to Enable Debug Logging for Active Directory Federation Services 2.0 (AD FS 2.0)
Set logging on in the fedlet - in FederationConfig.properties:
#com.iplanet.services.debug.level=error
com.iplanet.services.debug.level=message
Look at the SAML data - ADFS : I want to see the SAML data