Why doesn't Trace.axd show trace output after Server.Transfer?

[Chris Newby]

I have an asp.net 3.5 app with trace enabled and an HttpHandler that, under
certain conditions, calls Server.Transfer( "~/x.aspx", true ) from its
implementation of IHttpHandler.ProcessRequest.

The http handler works fine and calls Server.Transfer when I expect it to.
However I noticed that when viewing trace.axd for requests that call
Server.Transfer that the "Trace Information" section of trace.axd?id=xxx is
blank.

When I view trace.axd?id=xxx for aspx page requests that don't call
Server.Transfer everything is fine and I see the expected page events
outputted under Trace Information.

So a) what is going on, and b) what can I do to see trace output after a
call to Server.Transfer.

TIA//