If your clients are updating, than it's already a good sign.
how long ago have you placed the "upgrade" package into the install package for the group?
you should give it a little while (24 hours or so) for all the clients to be updated.
If you have x64 clients in there as well as 32 bit clients, you would need to have both intall packages there.
The interval for the client connectivity is random, so it could take some time. You can send a command to the group to "update content" might help push things along, as that almost assuredly force the clients to "check-in".
Cheers.