lilypond-book or latex doesn't find the necessary files

[Stefan Thomas]

Dear community,
in the below quoted latex-document, I get the following error:
test.tex:13:9: error: cannot find file: `rousselraga.ly'
This is my document and the file rousselraga.ly
%%%%%
\documentclass[a4paper,12pt]{article}
\usepackage[ngerman]{babel}
\usepackage[utf8]{inputenc} 
%\usepackage[paper=a4paper,left=20mm,right=20mm,top=25mm,bottom=25mm]{geometry} 
\title {From \grqq Krishna\grqq by Albert Roussel }
\author {Stefan Thomas}
\date { }
\begin{document}
\maketitle 
The following is a quote of the composition Joueurs de Fl\^ute by the french composer Albert Roussel.
\begin{lilypond}
\version "2.16.0"
\include "rousselraga.ly"
\new Staff  { \melodie }  
\end{lilypond}
\end{document}
%%%%%%%%
%%%%%% lilypondfile
\version "2.16.0"
zwozwozwoeeinsachtel = { \time #'(2 2 2 1) 7/8 }
    global = { \key a \major \zwozwozwoeeinsachtel }
    melodie = \relative c'' {
      \global
      r8 e \times 2/3 { f gis a } bes a gis |
    \bar"|." }