[OS X TeX] Problems with the index

[BenBehr]

Hi,
i have made the following tex file:

%%%%%%%%%%%%%
\documentclass{book}
	\usepackage[ngerman]{babel}
	\usepackage[utf8x]{inputenc}

\title{ESem}
\makeindex
\begin{document}

\tableofcontents

\part{Theorie}
\chapter{Dämmung}

\chapter{Dämmung}
Both Chapters should be the same!

\end{document}

%%%%%%%%%

After running Latex twice i get an pdf without any errors. But the  
index of the PDF is not correct. The first Chapter in the Index is  
D[Pleaseinsertintopreamble]mmung whereas the second chapter is  
displayed correctly as Dämmung.
I can't find what is wrong.

Thanks for any help,
Ben