Same with a bolt on toothbar. Those two bolts on the ends of the bucket just keep it from "falling off". The digging strength of the toothbar comes from the way the channel locks over the edge of the bucket.
That's why sometimes after heavy use the toothbar will be wedged so hard into the bucket cutting edge that you need to hammer it off.
I suspect there might be something on the OP's setup that is preventing the HH toothbar from seating all the way onto the bucket edge.