I'm trying to set ReferenceProperties in a ReplyTo; however whenever I send a
message with my reference properties, WSE throws an ArgumentException with
this message:

WSE002: The input was not a valid ReferenceProperties element because it has
either the wrong name or the wrong namespace. The name specified follows:
MyElementName. The namespace it was defined under follows: http://myuri.

The short question: How do I set reference properties for a ReplyTo?

The long question:

I've got a service 'A' which delegates to service 'B', and it's ok for 'B'
to reply directly to A's client so A doesn't have to handle the reply. How do
I do this? The WS-Addressing spec seems to imply reusing the message ID from
the client to A on the message from A to B is ok, but I can't set the message
ID with WSE (could I reuse the entire envelope, with some mangling?) I was
going to put a MessageID in the reference properties of the reply-to header
and have B build a RelatesTo from that, but then I ran into this problem.
Interestingly, ReferenceProperties has an explicit RelatesTo property, but if
I set this, it is not set/there are no elements at B.