What happens when you turn on your radio? Are there any lights on the Keg?
I don't know if the DDX 7025 has a "reset" button, but if it does, try to reset it. Sometimes Kenwoods need the reset to properly recognize the Keg. That was my experience anyway with my first Kenwood install, and I think the manual even specified this.
If it still won't work, it may be that your Keg has an older version of the firmware and was never updated. It might have worked with an older radio, but needs to be updated to work with yours.
You can check this on the DMS at your computer. Load the Phatnoise software, and then under tools, check the firmware options. It will tell you which version of the firmware is loaded on the DMS. If it shows any version less than 13.01, it probably means the firmware on the Keg is also old.