Error when customising ispell dictionary alist

Hello,

After a change from an old suse installation to a recent debian testing, I 
have an error when I try to configure ispells "Dictionary Alist".

What i do is:
M-x customize-group
ispell
<click on arrow next to "Dictionary Alist">

Then the complete entry of "Dictionary Alist" is vanished. I attached a 
stacktrace. All I can see from the stacktrace is, that the function 
"coding-system" doesn't exist, but I am no pro in reading lisp 
stacktraces...

The xemacs is XEmacs 21.4.17 "Jumbo Shrimp" configured for 
`i386-debian-linux`

What is wrong there ?

Best regards,

Markus Grunwald
Softwareentwicklung

PRÜFTECHNIK Condition Monitoring GmbH
Oskar-Messter-Straße 19-21
85737 Ismaning
www.pruftechnik.com
Tel: +49 (0)89 99616177
Fax: +49 (0)89 99616200