Windows GCC: Can't find my header

[PeterDa]

Trying to reactivate an ancient (2005) Windows GCC programme (and my C-knowledge) in Code::Blocks. My project includes an own file External.h in the Headers block, but

Code

#include "External.h"

gives 
fatal error: External.h: No such file or directory. Do I have to provide an additional reference somewhere?
-PeterDa

[BlueHazzard]

You have to set the search directory for the include files. This can be done in project-> build options-> search paths-> compiler

[PeterDa]

Thank you; I had seen this option, but assumed that - since the files were included in the project treelist - it wasn't needed here.
PeterDa

[BlueHazzard]

Thank you; I had seen this option, but assumed that - since the files were included in the project treelist - it wasn't needed here.

Headers are not passed to the compiler over command line,  so the project tree has no influence over this...