Including libraries from header files sometimes doesn't work I, once again have difficulties including libraries from code files other than my .ino file. 

I have several .cpp and .h files in my project to keep it sorted and clean. 
However one of my header files starting like this:

#ifndef DPLANDEF
#define DPLANDEF
#include &lt;Arduino.h&gt;
#include &lt;EEPROM.h&gt;
#include "syssettings.h"


yields the following errors:


  In file included from
  /var/folders/jl/nv1qvh6n569cxq9xxfd6dx980000gn/T/build4605486877500371361.tmp/dplan.cpp:2:0:
  /var/folders/jl/nv1qvh6n569cxq9xxfd6dx980000gn/T/build4605486877500371361.tmp/dplan.h:5:20:
  fatal error: EEPROM.h: No such file or directory  #include 
                      ^ compilation terminated. Fehler beim Kompilieren.


EEPROM.h should be known to the IDE, because I can find it in the libraries menu, too. If it was a custom library, I might have botched something during installation, but this is a standard library. It should work out of the box. What's the problem here?
The problem here is that it's a header file.  The IDE doesn't treat header files like it does INO files - it doesn't parse them for included libraries, etc.

In order for it to work you must also include EEPROM.h in your main INO file so that the IDE knows that you want to include it in the rest of your files.