[Spacewalk-list] Error installing or deploying RPM through Spacewalk

[Jason Ganovsky]

Hi, I have a test RHEL 5.1 server, subscribed to a single channel with a 
single RPM.  For some reason when I try and install or upgrade that RPM 
through Spacewalk, I get the following error message

D: Sending back response ((6,), 'Error while executing packages action: Public 
key for hello-1.0-18.1.i586.rpm is not installed', {})

The RPM is a very simple hello world test RPM.

Any ideas?