serious problem upgrading sox

[Bernard <bdebreil@teaser.fr>]

Hi to Everyone,

On my Debian Lenny system, the sox version that I had installed 
(v14.0.1) was somewhat outdated, so I tried to install 14.3, which 
appeared to be available only on 'testing' repositories. So, removed my 
v14.0.1, then I modified my /etc/apt/sources.list, and after an 'apt-get 
update', I reinstalled the newer version. I got no error that I can 
remember of, but then I found that, despites an up to date man page, the 
newer functions were not implemented in my "new" sox, which indeed must 
have still be the old one.

So, I removed it and tried to re-install the old version after removing 
the testing addresses in my /etc/apt/sources.list and updating. But this 
backstep appear impossible to achieve... The error messages, that are in 
French, can be summarized as follows : some packages cannot be 
installed. The following packages contain unsatisfied dependencies. sox: 
Depend: libsox0 but will not be installed
E: Defective packages

If I now try to call 'sox -h', I get this :
root@new-host:/home/bd# sox -h
sox: Symbol `sox_effect_fns' has different size in shared object, 
consider re-linking
sox: Symbol `sox_format_fns' has different size in shared object, 
consider re-linking
Segmentation error.

I have reached a point where I can no longer install a workable sox 
version. What can I do now ?

Thanks in advance for your help