newsimp.cl and taylor



hello,
I tried to taylor() with new simplifier loaded. Here's what I get

(C1) load("c:/src/mac/newsimp/newsimp.cl");

(D1) 			 c:/src/mac/newsimp/newsimp.cl
(C4) taylor(erf(x),x,0,10);


Error: addk given non-constants to add
Fast links are on: do (si::use-fast-links nil) for debugging
Error signalled by COND.
Broken at ERROR.  Type :H for Help.
MAXIMA>>:q

(C5) -1/2;

					1
(D5) 				      - -
					2
(C6) :lisp(print $d5)

-1/2
-1/2

....

MAXIMA>>(simplifya '((rat) -1 2) t)

((RAT) -1 2)
MAXIMA>>(simplifya '((rat) -1 2) nil)

((RAT) -1 2)
MAXIMA>>

So, where it transform from ((rat)..) to lisp's rational is done??? It's 
addk recieves ((rat)...) instead of a number from diffexpt... if I want 
to load new definition for diffexpt, what should I write to transform 
from ((rat)...) to a rational?
--
Andrei Zorine