[Tex/LaTex] xelatex doesn’t work with beamer and true type font

Question

I am trying to use a true type font in my presentation but I cannot do that withxelatex. Pdf is created although a warning is displayed but font is not chosen one. Warning is below:

(/usr/share/texmf-dist/tex/latex/beamer/translator/dicts/translator-theorem-dictionary/
translator-theorem-dictionary-English.dict)
! Extended mathchar used as mathchar (104865811).
<to be read again> 
               \relax 
l.7 \begin{document}

? 
(./basic.nav)

A basic presentation is like below.

\documentclass{beamer}

\usepackage[no-math]{fontspec}
\setmainfont[Mapping=tex-text]{Ahem}
\usepackage[defaultmathsizes]{mathastext}

\begin{document}
\title{Title}
\author{Author}
\maketitle
\end{document}

IS it possible to use true type fonts with beamer?

EDIT: Changing class to article produces expected result.

Answer 1

There is no problem with current TeXLive 2012. However, Ahem has only 4 "characters" XPE and <space> which can already be simulated by normal square rules. Then you do not need the font at all. My working example with Ahem:

\documentclass{beamer}

\usepackage[defaultmathsizes]{mathastext}
\usepackage[no-math]{fontspec}
\newfontface\ahem{Ahem}
\begin{document}
\begin{frame}
X PE \ahem X PE
\end{frame}

\end{document}