keyboard-translate working for Control but not for Alt

[Elena]

Hello,

since I use a Dvorak keyboard, I'd like to swap C-x and C-t, as it is
suggested here:

http://www.emacswiki.org/emacs/DvorakKeyboard#toc4

The proposed code performs its task:

http://www.emacswiki.org/emacs/DvorakKeyboard#toc4

(keyboard-translate ?\C-x ?\C-t)
(keyboard-translate ?\C-t ?\C-x)

Out of curiosity, I tried to swap M-x and M-t as well:

(keyboard-translate ?\M-x ?\M-t)
(keyboard-translate ?\M-t ?\M-x)

but evaluating each expression fail with (numbers are not the same):

Debugger entered--Lisp error: (wrong-type-argument characterp
134217848)
  keyboard-translate(134217848 134217844)
  eval((keyboard-translate 134217848 134217844))
  eval-last-sexp-1(nil)
  eval-last-sexp(nil)
  call-interactively(eval-last-sexp nil nil)

Software:
- Windows XP SP3
- GNU Emacs 23.1.1 (i386-mingw-nt5.1.2600) of 2009-07-30 on SOFT-
MJASON

Any help?

Thanks.