list sorting problem

[Mary Dalrymple]

Can someone help me with the sorting function?  I'm getting the following
behavior.

(setq before '(("FEATa" "NP4" "N" . "another comment about np")
 ("FEATURE" "NP3" "N" . "another comment about np")))

display before:

before's value is
(("FEATa" "NP4" "N" . "another comment about np")
 ("FEATURE" "NP3" "N" . "another comment about np"))

sort before:

(sort before (lambda (a b) (string< (car a) (car b))))

display before:

before's value is
(("FEATa" "NP4" "N" . "another comment about np"))

One of the list elements disappears.  This happens in Emacs 20.7.1.  Can
someone tell me what is going on?  Thanks --

 - Mary Dalrymple