completing-read-multiple in Emacs 21.x

[Sebastian Luque]

Hello,

I'm having problems with completing-read-multiple.  e.g.:


(completing-read-multiple
 "prompt: "
 '(("str1" 1) ("str2" 2)) nil t "str1,str2" nil "str1,str2")


When called, clearing the initial entry, and typing "s [TAB]" gives "[No
match]" in the minibuffer of Emacs 21.x.  This doesn't occur in Emacs
22.0.50.1.  In both versions though, the DEF argument (last one in the
expression above) seems to be completely ignored, as '("")' is returned in
the 22.0.50.1 version, and "[No match]" is displayed in the minibuffer of
Emacs 21.x.  Can somebody please point out what is going on or suggest an
alternative to reading multiple strings from a single minibuffer prompt?


Thanks,

-- 
Seb