Cylinder balance test?

[Speedwagon]

I bought the Actron code scanner for the older Fords today. Ran the KOEO and KOER with the scanner. In the book it talks about doing a cylinder balance test, and I'm doing as it says, but I never get any results. It tells me the test should take about 3 minutes. I've tried several times now, and this last time I waited 20 minutes before shutting the truck down.

Any ideas?