I have developed an add-in for ArcMap using the ArcObjects SDK for .NET and C#. My development machine is on 10.6.1 but I need to install the addin on machines with 10.5. I have done this in the past.
My add-in consists of a toolbar containing several buttons. I can install the add-in on the 10.5 machines but when I click the buttons they immediately become grayed out.
In Visual Studio on my development machines, I have targeted the add-in to the .NET framework installed on the target machines, and set all the references assemblies to Copy Local.
What else can I try?