Hello, I've had my ebike a couple of years and now want to use it for commuting. I've bought a pair of Acid panniers and am having trouble getting them to sit securely. The top bracket hooks on nicely to the built in rack, but the bottom mount is not so secure. The whole thing seems to come off far too easily. I can't seem to find any information or images about how or where it attaches, or if I need to buy another attachment. I'm very confused, anyone help please?