Special characters/diacritics in the Author or Title field of a transaction will break the search for the Get It Now addon. The characters appear as they should in the client, and the URL works outside of ILLiad, but when left in the fields the search breaks. Once the characters are removed/replaced it works fine.

Bug# 7600

If a system addon is created but FormNames are also entered, the addon will be loaded for both the system script environment and for each form script environment that is specified. An example where this causes errors is when registering system event handlers which can only be registered to a single addon.
 
Forms are not relevent in Library, System, or Server addons.