maxima does not differentiate anymore



Hi all,

after noticing that Bruno Haible had posted an updated version of 
clisp, I compiled and installed it.
Then I recompiled Maxima.

All went well.
Or so I thought.

After several hour's work with Maxima, I suddenly noticed that the 
differential operator diff(y, x) returns unevaluated.

My Fink-installation of Maxima (I use OS X) works fine.
(This installation has a clisp-maxima file in /sw/bin)


Any ideas?

Thanks in advance.

Marc Charpentier