CentOS 5 :: Installing Rtorrent - Package Requirements Not Met

I'm completed new to Linux and centos. I've tried to install rtorrent and installed these packages:

Openssl:
=======
[root@server2 bin]# rpm -qa | grep openssl*
openssl-perl-0.9.8e-7.el5
openssl-devel-0.9.8e-7.el5
openssl-0.9.8e-7.el5
openssl-devel-0.9.8e-7.el5
openssl-0.9.8e-7.el5
[root@server2 bin]# yum list installed openssl*
Loaded plugins: fastestmirror, priorities
Installed Packages
openssl.i686 0.9.8e-7.el5 installed
openssl.x86_64 0.9.8e-7.el5 installed

pkg-config:
=======
pkgconfig.x86_64 1:0.21-2.el5 installed
libsigc++
======
libsigc++20.x86_64 2.0.17-1.el5.rf installed
libsigc++20-devel.x86_64 2.0.17-1.el5.rf installed
cUrl
====
curl.x86_64 7.15.5-2.1.el5_3.4 installed
nCursess
======
ncurses.i386 5.5-24.20060715 installed
ncurses.x86_64 5.5-24.20060715 installed
ncurses-devel.i386 5.5-24.20060715 installed
ncurses-devel.x86_64 5.5-24.20060715 installed

For some of them I used apt-get ( yes I had to install apt first) and the other, I used yum.
But when I run ./configure in libtorrent-0.12.4 directory, I get this error at the end of it's process:
checking pkg-config is at least version 0.9.0... yes
checking for OPENSSL... configure: error: Package requirements (openssl) were not met:
No package 'openssl' found
Consider adjusting the PKG_CONFIG_PATH environment variable if you installed software in a non-standard prefix. Alternatively, you may set the environment variables OPENSSL_CFLAGS and OPENSSL_LIBS to avoid the need to call pkg-config. See the pkg-config man page for more details.
What should I do to install it?