Description of problem:
situation
client A and B are subscribed to the global rhel3 channel with a local
subchannel with a bunch of packages. Including package foo-1.1 and
foo-1.2.

client A has foo-1.1 installed, client B does not have foo installed
but is otherwise identical package wise.
Via website, make profile of client A.
Via website, compare client B with the profile, and choose to install
the differences. 
Client B will then try to get foo-1.1 but somehow RHN tells it that
package doesn't exist (although it is in the subchannel).

It works if you use the latest version, but it also works if you
remove foo-1.2 from the subchannel via the webinterface, eg foo-1.1
becomes latest.