It may just be that I didn't upgrade jEmpload properly.

Possibly. You must download the latest JAR file by hand and run it by itself. Where did you get that JAR file from?

Also, you have to realize that Jemplode only works over ethernet. If you are trying to use the USB connection to the Karma, then it won't work.

If you have the right JAR file and you're using ethernet, it's possible that you haven't set up ethernet properly on the Karma. Can you see the Karma via ethernet with RMM?

If you can't see the Karma via ethernet at all, check the lights on the ethernet port on the dock. If they are both lit up solid (instead of one solid and one off or blinking), then the karma is incompatible with your hub and we're on to a whole other diagnostic process at that point.