Card Space exception: incoming policy failed validation
One possibility is that your binding does not contains required claim types. In your client binding, make sure you have at least one required claims:
WSFederationHttpBinding
binding = new WSFederationHttpBinding( WSFederationHttpSecurityMode.Message );
// the required claim sections
binding.Security.Message.ClaimTypeRequirements.Add( new ClaimTypeRequirement( ClaimTypes.Name ) );
// the optional claim sections
binding.Security.Message.ClaimTypeRequirements.Add(
new ClaimTypeRequirement( ClaimTypes.Gender, true ) );
Hope this helps