[AUCTeX] Problem with Latex command-completion (M-TAB)

[Ralf]

Problem: The Latex complete-command macro (M-TAB) is only recognizing a few
commands.

Examples:

\secti completes to \section.

\texti fails to complete to \textit, with error message "Can't find completion
for \texti".  In contrast, the Latex-insert-font macro happily inserts \textit.

I could fathom the problem if complete-command failed for all commands,
but why does it work for some commands and not for others?

One other clue.  When I try to complete \textb,  complete-command fails to find
\textbf but does list three other possibilities, \textbackslash, \textbar and
\textbullet.

Details:

auctex-11.84, emacs-gtk-22.2 and texlive-2007 on ubuntu-jaunty.

My .emacs file contains the three basic Auctex variables,

TeX-auto-save t
Tex-master nil
TeX-parse-self t

A sample .tex file which illustrates the problem follows:

%%% Local Variables:
%%% mode: latex
%%% TeX-master: t
%%% End:
\documentclass[10pt]{article}
\title{A Test Title}
\author{A Test author}
\begin{document}
\maketitle
\section{Test Section}

The \texti

\end{document}