[OS X TeX] Missing $ inserted in a "variations" environment

[ewan.Delanoy at math.unicaen.fr]

>Since you don't give a complete, compilable example

  Sorry, I explained badly. The code below is a full,
minimal example that you will be able to re-compile
in a flash.

>things like \alpha and \beta I know that they need
>to be in math mode.

  I tried miscelleneaous thing like that, such as
wrapping the \begin{variations}(...)\end{variations}
inside a "\begin{dispalymath}(...)\end{displaymath}",
or putting $'s around \alpha and \beta : this did not
fix the problem.

   Besides, I already used successfully the "variations"
environment without having to insert math mode at all.

                   Ewan

A minimal (16-liner) example :


\documentclass{article}
\usepackage{variations}

\begin{document}

\noindent \makebox[\textwidth][c]{
 \begin{variations}
   x  & \mI  &   & \alpha& & & 1 & & \beta&  & & 2 & & \pI & \\
   \filet
 f'(x) & \bg & + & \bb&  & + & \z & -& \bb & & - &\z& + & &\bd \\
 \filet
  \m{f(x)} & \bg \mI &  \c \h{\pI} & \bb& \mI & \c & \h{-1} & \d \mI & \bb
& \h{\pI}& \d &\frac{3}{2}& \c
  & \h{\pI} & \bd \\
\end{variations}
}
\end{document}