I would hazard a guess that your issue is related to the communications protocol of the servos. By default most of those library examples use Protocol 2 Communications, while the AX-18 uses Protocol 1. You can check this by changing this line to target Protocol 1.
If this isn't the cause of your problem it would be helpful if you could share some more details about what's going on. As sterretje mentioned, it might be difficult for people to figure out what the root cause of the issue is without more information.