LinuxQuestions.org - ./configure -- never glib-2 found!! Help plz

Hello again,

As I would like to compile some sources (this time, XFCE4), running ./configure first is needed. Then, the config thing checks for everything if it is correctly installed. I get this error:

Quote:

checking for glib-2.0 >= 2.0.0 gtk+-2.0 >= 2.0.0... Package glib-2.0 was not found in the pkg-config search path.
Perhaps you should add the directory containing `glib-2.0.pc'
to the PKG_CONFIG_PATH environment variable
No package 'glib-2.0' found

What the hell, glib is installed correctly!! (Im running Fedora beta 3, with latest updates and stuff) Well anyway, I installed the newest glib I found on the internet with TAR and RPM. When searching for it (using "locate glib") or (using rpm -qa | grep glib) I can see my glib and it IS installed.
MOD: in my dir /usr/local/lib/pkgconfig is a file glib-2.0.pc wich is a part of the glib I installed. There's also a glib-2.0 dir inside /usr/local/lib (only 1 file in the subdir include) and there's a lot of sh*t inside /usr/local/include/glib-2.0 so what the heck it is definitly installed.

But this is not XFCE, when I try to install something else wich depends on glib it gives that error too... (Most oblivious, but heck)

Could someone help me?
Did I configure something wrong or so?
What's up with that PKG_CONFIG_PATH?
Thanks a lot guys!!