[racket] Exception Stack Trace Troubles

Hi,

Is there some sort of 'secret' to acquiring the stack trace of an
exception?  It is my understanding that when an exception is raised
with  the 'error' procedure in creates a exn:fail structure that has a
message field and a continuation-marks field.  Presumably the stack
trace is in the continuation-marks field.  To actually get the stack
trace I need to call the following:

(continuation-mark-set->context (exn-continuation-marks exception))

However, whenever I call this, it yields an empty list: ()  - Not a stack trace.

Am I doing something wrong?  Any help is greatly appreciated.

--
Chad