Problem with special german in LaTeX mode of XEmacs

Hello list,

I'm running xemacs-21.5.21.20050721-4 (SuSE 10.0), and suddenly I've prob=
lems=20
with german umlauts. The umlaut for a should be presented by "a, whenever=
 I=20
type umlaut a on my keyboard (for guys who have the appropiate code page =
here=20
the letter: =C3=A4). If LaTeX find the "a combination, it will print the =
correct=20
umlaut a.

To get this, I've first defined:

(fset 'ae "\C-q42a")

and later

(local-set-key 'adiaeresis 'ae)

in my init.el xemacs config file.

However, If i type the umlaut a key, I get only the " (quote) character, =
and=20
The following error is displayed in the mode line:

Wrong type argument: command-event-p, ?a unread-command-event

The error never occurs before, and I haven't changed my config file.

What is wrong?

Alexander