I was having the same problem, but fixed it by clicking on the right thing in Google Earth before saving the KML file. From my reading of the instructions, I thought I was supposed to right-click on the first direction in the list. Instead, you should right-click on the very first entry in the list; the one that shows overall route.
So, when I created a route from Mayer, Arizona, to Prescott, Arizona, the correct entry to click on is the one that reads, "Mayer, Arizona to Prescott, Arizona," not the one that says, "Head southwest from Old Sycamore Rd."
Step 4 in the instructions on how to create and save the KML file could be clearer. You know what they say the problem with making things idiot-proof is: idiots are so darn ingenious.
Hope that helps.