Hello, I'm currently reworking KittsMenuSystem like A LOT, I guess I should've have been more specific in the README.md file, KittsMenuSystem is technically its own plugin, it does not work the exact same, so you cannot migrate it over as easy (should still be straight forward), just like ThatGuy said post the logs, and make sure to enable debugging in the config.
As I did say in that previous message something was broken and I am working on a fix, I was hoping it'd be a small bug fix and actually take 16 hours but now I'm reworking the whole thing and it's going to take 3 days (today is day 3), because KittsMenuSystem is going to be reworked in the update it means that again, it will not work exactly like SSMenuSystem, although the the framework will be similar and again, should be easy to migrate.
One more thing, when you do find bugs (even in other plugins), it's best to @ the OP so they can get pinged, I didn't see this until just now.