Okay, just to double check a few things:

What firmware version is on your player? What color is your RioStick? If the answers to those questions are 2.43 and black respectively, than you have a new version of the Cali that supports MSC. The version of RMM that came on the CD with your Cali (should be 2.85) is newer than what you have for your Karma, and is required to use your Cali with RMM. The Karma will work fine with the new version, however, as long as you don't uninstall the old version first. Just install the new version on top of the old version, and the Karma drivers will stay installed and work just fine with the new RMM.