Hi Dan, I haven't used CMS a long while and don't have access to a running instance for Avayab but I'd try the following.
Try the SetObject method instead of GetObject up see if makes a difference.
You may have more one instance of the server object running, server 2, 3, 4 ... this happens if one hangs. Look at windows task manager to see if it's the case. You'll find multiple processes are running. A reboot will be the easiest way to get rid of the orphaned objects.
Try using early binding to narrow down the cause by adding references to the Avaya libraries to see if it works and if a recent update caused a change in the naming of the ACS objects. I have a feeling that's the issue from memory when I moved to R19, in the tool you be able to see the new name of the class. Like instead of ACSCN it will be ACUN or something like that.
Check of you are still using the 32 bits excel not the 64bits.
I've seen a techniques where using the full path to the exe/Dll as an argument instead of the class name in get or setObject might help if the class has become unregistered.
Thse are just few things to try. But i have a feeling the class been renamed between these versions of CMS. Look at some other threads on this forum and compare the code a as i think this was discussed before.
