[CentOS] Nessus Installation Failure

I'm trying to get get nessus 2.2.5 to install on my centos 3.5 system. It errors out with this error:

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x - Compiling the libraries x -- Configuring the sources for your system configure: error: Could not find OpenSSL and OpenSSL headers on your system **** An error occured :/ Do you want to save the compilation log to analyze what went wrong ? [y] Where should I save this file ? [/root/nessus_compilation] Do you want to delete /tmp/nessus-installer.11739 ? [y]

rpm -qv openssl shows:

[root@asskicker em]# rpm -qv openssl openssl-0.9.7a-33.15

Anyone have any ideas as to what I'm doing wrong or what I need to change to get this package to install?

Thank you,

Ed