Problem using gtk+-2.0.4

[Gandalf <gandalf55 wanadoo fr>]

Hello,

I want to use the util "gpa" (GnuPG Assistant) on Linux Mandrake 8.0 but 
that required the utilisation of gtk because xhen I execute ./configure 
of "gpa", it's said:

*****
Checking for GTK - version >= 1.2.1 no
"The gtk-config script installed by GTK could not be found
If GTK was installed in PREFIX,  make sure PREFIX/bin is in your path or 
set the GTK_CONFIG environment variable to the full path of gtk-config"
*****

I don't unserstand why because I followed all the stapes indicated on 
website of GTK. That means that I installed before GLib, Pango, ATK, 
JPEG and TIFF libraries.

Before, I made "./configure --prefix=/opt/gtk", "make" and "make 
install", I enter the following lines into my .bashrc file:

CPPFLAGS=-I/opt/gtk/include
LDFLAGS=-L/opt/gtk/lib
PKG_CONFIG_PATH=/opt/gtk/lib/pkgconfig
export CPPFLAGS LDFLAGS PKG_CONFIG_PATH

LD_LIBRARY_PATH=/opt/gtk/lib
PATH=/opt/gtk/bin
export LD_LIBRARY_PATH PATH


Thank you for all answers!