I’ve already purchased EZKeys Hybrid Harp and also have the Mellotoon sound expansion.  Yesterday I purchased an EZKeys Sound Expansion through Sweetwater. When I went to register my serial number and make my selection (Small Upright Piano) I received an error message that stated I need to have an already registered EZKeys product and listed each of the EZKeys instruments. I noticed all the EZKeys instruments were on the list EXCEPT the Hybrid Harp. I called Sweetwater and they said I should be able to register the sound expansion since I already pushed an EZKeys core instrument.
Why can’t I add a sound expansion if I’ve already purchased EZKeys Hybrid Harp?