[Spacewalk-list] Updates available but yum won't update

[Sam Juvonen]

I have a RHEL5 channel in my spacewalk server and it shows that there
are 50 packages available for a newly installed server (was installed
from CD images). The SW server is a newly installed 1.4.

However, on the client itself, yum doesn't see them:

# yum clean all; yum repolist
Loaded plugins: rhnplugin
epel                                                                                                                                     
| 3.7 kB     00:00
epel/primary_db                                                                                                                          
| 3.7 MB     00:01
spacewalk                                                                                                                                
| 2.1 kB     00:00
spacewalk/primary_db                                                                                                                     
| 133 kB     00:00
spacewalk-client                                                                                                                         
| 2.1 kB     00:00
spacewalk-client/primary_db                                                                                                              
|  10 kB     00:00
repo id                                                     repo
name                                                                             
status
epel                                                        Extra
Packages for Enterprise Linux 5 -
x86_64                                         enabled: 6,466
rhel5-server-x86_64                                         Enterprise
Linux 5
x86_64                                                             
enabled:     0
spacewalk                                                  
Spacewalk                                                                             
enabled:   205
spacewalk-client                                            Spacewalk
Client
Tools                                                                
enabled:    21

See that rhel5-server-x86_64 line - why is it showing 0 packages available?

Clues welcome...