RHEL 5.7 yum conf? ('yum grouplist' failing)

I have root access (2+ yrs of Centos experience),
but I'm new to RHEL. It's possible this is "basic"..:

Pls consider:

  [root@ourhost01 ~]# lsb_release -a
  LSB Version:    :core-4.0-amd64:core-4.0-ia32:core-4.0-noarch:graphics-4.0-amd64:graphics-4.0-ia32:graphics-4.0-noarch:printing-4.0-amd64:printing-4.0-ia32:printing-4.0-noarch
  Distributor ID: RedHatEnterpriseServer
  Description:    Red Hat Enterprise Linux Server release 5.7 (Tikanga)
  Release:        5.7
  Codename:       Tikanga
  [root@ourhost01 ~]# uname -a
  Linux ourhost01.ourbiz.local 2.6.18-274.el5 #1 SMP Fri Jul 8 17:36:59 EDT 2011 x86_64 x86_64 x86_64 GNU/Linux
  [root@ourhost01 ~]# yum repolist all
  Loaded plugins: security
  repo id                  repo name                                                    status
  base-local               Redhat 5.6                                                   enabled: 3,357
  rhel-debuginfo           Red Hat Enterprise Linux 5Server - x86_64 - Debug            disabled
  rhel-debuginfo-beta      Red Hat Enterprise Linux 5Server Beta - x86_64 - Debug       disabled
  rhel-source              Red Hat Enterprise Linux 5Server - Source                    disabled
  updates-local            Redhat 5Server - x86_64 - Updates                            disabled
  repolist: 3,357
  --snip: is the soln as simple as enabling all or some of the disabled repos?
  --snip: why is "base-local" labeled '5.6' not '5.7'?
  [root@ourhost01 ~]# yum info yum
  Loaded plugins: security
  Installed Packages
  Name       : yum
  Arch       : noarch
  Version    : 3.2.22
  Release    : 37.el5
  Size       : 3.3 M
  Repo       : installed
  Summary    : RPM installer/updater
  URL        : http://yum.baseurl.org/
  License    : GPLv2+
  Description: Yum is a utility that can check for and automatically download and
             : install updated RPM packages. Dependencies are obtained and downloaded
             : automatically prompting the user as necessary.

  [root@ourhost01 ~]# yum update
  Loaded plugins: security
  Skipping security plugin, no data
  Setting up Update Process
  No Packages marked for Update
  [root@ourhost01 ~]# yum grouplist
  Loaded plugins: security
  Setting up Group Process
  Error: No group data available for configured repositories
  [root@ourhost01 ~]# yum groupinstall "Development Tools"
  Loaded plugins: security
  Setting up Group Process
  Warning: Group Development Tools does not exist.
  No packages in any requested group available to install or update
  [root@ourhost01 ~]# ls -l /etc/yum.repos.d
  total 12
  -rw-r--r-- 1 ouradmin0 ouradmin0 349 Dec 15 18:12 localrepo.repo
  -rw-r--r-- 1 root      root      561 Jun 29 03:23 rhel-debuginfo.repo
  -rw-r--r-- 1 root      root      222 Jun 29 03:23 rhel-source.repo

Note my comments after the '--snip' string above.

Is yum configured normally, ie is there something obviously wrong?

What might be done to allow the 'yum update', and 'yum groupinstall'
commands to work.

I'm unfamiliar w/RHEL repos, and disabling/enabling repos.

*Thanks* much for any suggestions.

--
Tom

--
I'm not the primary administrator for this 'dev' server.