Installed package not found

Hello!

I'm trying to add the 'libfprint' package into Buildroot. As I read in the site of the project, the requisites are glib2, libusb-1.0, ImageMagick and nss3 in the current version (0.4.0). As I can't found nss in the Buildroot, I 'downgraded' the version, trying to install the version 0.0.6. Well, the config files are the following:

## Config.in ##
config BR2_PACKAGE_LIBFPRINT
bool "libfprint"
help
The libfprint is a library for biometric
fingerprint development.

http://www.reactivated.net/fprint/wiki/Libfprint
## end Config.in ##

## libfprint.mk ##
#############################################################
#

# libfprint
#
#############################################################

LIBFPRINT_VERSION = 0.0.6
LIBFPRINT_SOURCE = libfprint-$(LIBFPRINT_VERSION).tar.bz2 LIBFPRINT_SITE =
http://sourceforge.net/projects/fprint/files/libfprint/v$(LIBFPRINT_VERSION)/libfprint-$(LIBFPRINT_VERSION).tar.bz2/download
LIBFPRINT_INSTALL_STAGING = YES LIBFPRINT_INSTALL_TARGET = YES LIBFPRINT_DEPENDENCIES = libglib2 imagemagick libusb

$(eval $(call AUTOTARGETS,package,libfprint))
## end libfprint.mk ##

First, the download link isn't ok, but I'll fix it later (the current version is git hosted). For tests, I put the file manually in the dl folder. My main problem is that, in the ./configure script, the process stops saying that 'No package 'libusb' found', but it is installed. Someone can help me?