Unable to click on Object with token (Logout button)

Hi, I’m newbie and studying with Katalon.

I’m trying to check the Login and Logout function of this site: schoology.com
I also try to apply Custom Keyword following this article: Unable to click on Object

My tests works fine with most Objects, but there is 1 Object with token (Logout button) led to these Error message:
- com.example.WebUIKeywords
- Test Cases/Schoology.com FAILED because (of) java.lang.ClassNotFoundException: com.example.WebUIKeywords

When I try to inspect this Object (Logout), it returns: Logout

Could you guide me how to resolve these errors?
Thanks in advance!