Defsystem: trouble with module-group

Hi 

I am trying to move my building rules from  ASDF[lst:1] 
to Allegro defsystem[lst:2]

A simplified version is.

;;; listing 1
(asdf:defsystem foo-system
    :components 
  ((:module :foo
            :components
            ((:file "a-file.lisp"))
            :depends-on (:bar))
   (:module :bar
            :components
            ((:file "another-file.lisp")))))
            
The directory structure is 

/path/to/foo/src/
                 foo/
                 bar/

The subsystem in foo depends on bar.

;;; listing 2
(defsys:defsystem :foo-system 
    (:default-pathname #p"/path/to/foo/src/")
  (:module-group foo
                 (:serial bar "foo/a-file.lisp"))
  (:module-group bar
                 (:parallel "bar/another-file.lisp")))

Is this the correct way to specify that module-group foo
dependes on module-group bar?

;   Compiling system: "bar".
;   Compiling module foo/a-file  ERROR

Nothing in bar is getting compiled or loaded.

What am I missing?


Thank You

Torkel Holm