Help with 7th Axis Setup in RobotStudio

Anyone have a link to a tutorial on how to setup a 7th axis in Robot studio? I'm trying to add a rail to a IRB4600, and according to what I can find in the literature, it looks like it is supposed to be as easy as just dragging the robot onto the rail, and rebooting. However, I get the error "Invalid mechunit for coordinated motion. No mechunit configured for mechanism 'IRBT2005_IRB_STD_EXT_500_90_4__01'." and the RobotStudio prompts me to remove the robot from the rail.

Thanks for the link. It was really helpful, since it included a working 7th axis cell. I was able to compare and contrast and find what was wrong with my setup.

Key things wrong:

1. I didn't run the extended axis wizard, since I wasn't aware where it was. Its slightly hidden:
   1. You run it under the virtual controller menu.
   2. 
2. Once I ran that, the robot would run on the rail, but movement wasn't coordinated.
   1. Had to go under the control panel settings, then under motion, then under robot, and then set the setting "Robot base moved by" to the name of the track.

Once I had that set, the robot now jogs correctly, and you can to do the typical "keep the TCP stationary and jog the 7th axis" type moves.