libraries... no such file or directory

D:\Peters Dateien\Dokumente\Arduino\arduino-1.0.1\libraries\DallasTemperature\DallasTemperature

But this problem ocurred with other devices too, for example with the Metro library, or the libraries for DCF 77,and, though the #include statetement was written in the sketch,
i tried to include the library with sketch-import library..