[CentOS] Identical yum configs, different results

Hi all,
 
I have two new Centos 5.2 servers ("drizzle" and "fog"), both ROCKS headnodes installed from the same rolls.  Identical `uname -a' output (2.6.18-92.1.13.el5, x86_64 etc), identical yum versions (Version: 3.2.8 Release: 9.el5.centos.1) with identical yum.conf files and identical repo files in /etc/yum.repos.d.
 
To simplify things I've disabled all repos except the centos base on both servers:
 
   [base]
   name=CentOS-$releasever - Base
   mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os
   baseurl=http://mirror.centos.org/centos/$releasever/os/$basearch/
   gpgcheck=1
   enabled=1
   gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5

Octave is installed on drizzle:
 
    drizzle@/etc/yum.repos.d# yum info octave
    Loading "fastestmirror" plugin
    Loading mirror speeds from cached hostfile
     * centosplus: mirrors.portafixe.com
     * base: mirrors.portafixe.com
     * updates: mirrors.portafixe.com
     * extras: mirrors.portafixe.com
     * addons: mirrors.portafixe.com
    centosplus                100% |=========================|  951 B    00:00     
    base                      100% |=========================| 1.1 kB    00:00     
    updates                   100% |=========================|  951 B    00:00     
    extras                    100% |=========================| 1.1 kB    00:00     
    addons                    100% |=========================|  951 B    00:00     
    Installed Packages
    Name   : octave
    Arch   : x86_64
    Epoch  : 6
    Version: 3.0.1
    Release: 2.el5
    Size   : 33 M
    Repo   : installed
    Summary: A high-level language for numerical computations
    Description:
    [etc...]
 
And I'd like to install it on fog; however:
 
    [root at fog yum.repos.d]# yum info octave
    Loading "fastestmirror" plugin
    Loading mirror speeds from cached hostfile
     * base: mirrors.portafixe.com
     * updates: mirrors.portafixe.com
     * centosplus: mirrors.portafixe.com
     * addons: mirrors.portafixe.com
     * extras: mirrors.portafixe.com
    Error: No matching Packages to list
    [root at fog yum.repos.d]#

"yum install octave" gives the same error.
 
Any idea what I'm missing?  I'm sure it's something stupid but I've been banging my head against the wall all evening on this...
 
Thanks,
-Rob
Rob Hutten
Senior HPC Engineer
Flagstone RE
Suite 700, Cogswell Tower
2000 Barrington Street
Halifax, Nova Scotia B3J 3K1
www.flagstonere.bm

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