StepTalk and object construction.

(Note I am using cvs -q -d 
":ext:[email protected]:/cvsroot/gnustep" update -dP -D 20041203 
gnustep/dev-libs/StepTalk)

I tried the following example code from ESUG2003 slides:
| object method source engine |
    object := STScriptObject scriptObject.
    engine := STEngine engineForLanguageWithName:'Smalltalk'.

    source := 'sayHi Transcript show: \'Hi.\'. ^self'.
    method := engine methodFromSource:source
                     forReceiver:object
                     inEnvironment:Environment.

    object addMethod:method.
    object sayHi.

with stexec and I receive the error:
"stexec: Uncaught exception STInterpreterGenericException, reason: No 
execution environment set"

I can get the method to execute 'manually' by using 
"executeMethod:forReceiver:withArguments:inEnvironment:". 

Why can't I get it to work as written?

Thanks,

Matt