Unable to receive SOAP fault from WCF service - wcf

Question

I am trying to send a soap fault from BizTalk to a .NET client. BizTalk has no out of the box way of exposing fault contracts so I am creating the fault message in a messageinspector (BeforeSendReply)
I have a .NET client that has a service reference to the BizTalk without any knowledge of the fault contract. The BizTalk WCF service is configured to receive a request and return a fault (for testing).
When the client receives the fault from BizTalk I get:
"The server did not provide a meaningful reply; this might be caused by a contract mismatch, a premature session shutdown or an internal server error."
When I turn on message tracking I can se that a fault message indeed is tracked at the transport level.
<s:Envelope xmlns:s="http://www.w3.org/2003/05/soap-envelope" xmlns:a="http://www.w3.org/2005/08/addressing">
<s:Header>
<a:To s:mustUnderstand="1">http://www.w3.org/2005/08/addressing/anonymous</a:To>
</s:Header>
<s:Body>
<s:Fault>
<s:Code>
<s:Value>s:Client</s:Value>
</s:Code>
<s:Reason>
<s:Text xml:lang="en-US">BTSError</s:Text>
</s:Reason>
<s:Detail><DaxFaultContract xmlns="http://MyNamespace">
<ErrorCode>1</ErrorCode>
<ErrorText>This is an exception</ErrorText>
</DaxFaultContract></s:Detail>
</s:Fault>
</s:Body>
</s:Envelope>
I thought, that even without any knowledge of DaxFaultContract the client would be able to throw a untyped FaultException.
What have I missed?
EDIT:
This actually works for WSHttpBinding. The problem occurs when using net named pipe binding. What is the difference in this case?

Answer 1

The problem was that the soap header "RelatesTo" did not get passed along to my fault message so when the client received the fault message it did not know what to do with it.
I guess that WSHttpBinding does not use the RelatesTo header in the same way that NetNamedPipeBinding does?