Tooltips in C3.js bar graph

I have an already working function able to show a bar graph done with [login to view URL] from a PHP app that is preparing data in JSON format. My goal is to be able to show more info in the tooltip of each bar but anytime I try to do that I get NULL info even if the JSON itself is correct and gives back the exact amount of columns I want to show in the exact format [login to view URL] is waiting for to map them in the graph. In the attached example, all is fine till "Vehicle Count" then the rest is shown as NULL. A second small problem. Is there a way to modify standard YII gridview pager to allow a "lazy loading" or "endless scroll" pager? If yes I need to see how this can be done (code examples). See attached image (example-load_more) showing from what it is now, Page numbers left to right and how we'd like to have it, loading more pages when the user wants to see more.