Problem installing duplicity 0.6.21

Last messages:
...
running build_ext
building 'dublicity._librsync' extension
creating build/temp.linux-i686-2.7
creating build/temp.linux-i686-2.7/duplicity
gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -02 -Wall -Wstrict-prototypes -fPIC -I/usr/include/python2.7 -c duplicity/_librsyncmodule.c -o build/temp.linux-i686-2.7/duplicity/_librsyncmodule.c:25:20: schwerwiegender Fehler: Python.h: Datei oder Verzeichnis nicht gefunden
Kompilierung beendet.
error: command 'gcc' failed with exit status 1