Problems in files included using relative paths

I am having a problem #including files that reference other files by
relative paths.  For example, when #including "math.h" in the Symbian
7.0 SDK, I get errors when "math.h" attempts to include "sys/reent.h"
and "machine/ieefp.h".

In reading other posts regarding this issue, it seems that a potential
fix is to enable source relative includes in the Access Paths settings.
 Unfortunately, this checkbox is disabled and I can't for the life of
me figure out how to enable it.

I am using "CodeWarrior Development Studio for Symbian OS, Version 3.1,
CodeWarrior IDE v 5.5.4.1621".

Thanks!
David Brownell