pdflatex short-cut keys

[Christian_Yale]

hi there,

I want to have a short-cut key for running latex (under pdf mode) in
emacs22, then i do not need to click the icon (the lion one, where
appear 'Run LaTeX' if you put the mouse over it) for doing so. I put
the following in my .emacs file, but it did not work (i wanted to get
"ALT+t" to run latex):

 (list "pdfLaTeX" "pdflatex '\\nonstopmode\\input{%t}'" 'TeX-run-LaTeX
nil t)

        (global-set-key "\M-t" 'do-pdflatex)
        (defun do-pdflatex ()
              "pdflatex the current file."
              (interactive)
              (TeX-command "pdfLaTeX" 'TeX-master-file))

but, is not working at all, I mean when i "ALT+t" appear a message (in
emacs) that says

Wrong type argument: stringp, nil

Any suggestions?

Thanks in advance
!!
Ps: about my PC-emacs stuff
I use emacs22 (under ubuntu-linux 7.10), with auctex and ess, to be
able to compile LaTeX and R files from only one program.
Within emacs22 i have installed ECB (http://ecb.sourceforge.net/) and
Org-Mode (http://orgmode.org/), and I also use subversion (http://
subversion.tigris.org/) as the basis of
project and R code version control.