why i can see the button of "invite to chat" and "engage chat",but can't use it when i select a visitor

hi , everyone , im new of here , and im a chinese , i have so many problem for use the liveperson , bcs my english is very poor;

my first problem :

why i can see the button of "invite to chat" and "engage chat", and i can click it when  select a visitor , but there no response in the visitor page.