Kata Hexabag 3/Insertrolley question

[Philip Fass]

A few years ago, Kata sent me a retrofit kit for the Hexabag/Insertrolley. (Bag used to flop off the trolley.) The kit includes a flat, black cloth object, about 4xx5 inches, that looks like a pouch and fits inside the bottom of the trolley. It also has a belt that's about the diameter of the Hexabag.

Problem is, the bag slipped out of the trolley today, and that belt is hanging loose. I can't figure out where it goes or what it attaches to, and I don't see it mentioned on the Kata website.

Any suggestions? Thanks.