How are you including the that header file?
With
#include "file.h"
or with
#include <file.h>
?
If you are using <...>, then add it to the 'System Path' directory list.
And: is the error produced by the compiler (present in the console view) or by Eclipse (just marked in the Editor view)?
If it is just in the Editor view, I think this was an issue with Eclipse (not with the compiler).