Camera Adapter Plug Does Not Fit

We purchased Canon Rebel cameras and the 3rd party adapter in the parts list: “ACK-E15 7.4V 2A”. But the adapter’s plug does not fit into the hole in the Rebel camera – the diameter of the plug is too large. Are we supposed to cut off the existing plug and replace it with a 2.1mm x 5.5 mm plug? Does anything need to change in the parts list because of this?

Did you get a response to this? Basically the small plug should be going into something that looks just like the battery, not the ports on the side of the camera.

I replied to this, but apparently in another topic.