FMC in Tutorial - Copy to SET POS fails

When following tutorial set-up - Pg14 - Setting LESA N40 57.12 005 30.12 to AIRPORT then 2RK to copy - then when pressing 5RK to insert to SET POS, this 2RK to 5RK step is imtermittent, sometimes it works, sometimes not. Mostly not. Am I missing a step?

I can spend whole hour and it won't work. Tried re-starts and re-loads.

Model Name: iMac

  Model Identifier: iMac8,1

  Processor Name: Intel Core 2 Duo

  Processor Speed: 2.8 GHz

  Number Of Processors: 1

  Total Number Of Cores: 2

  L2 Cache: 6 MB

  Memory: 4 GB

  Bus Speed: 1.07 GHz

Did you turn IRS knobs to nav position starting from cold and dark, or from engines running first them to off and then to nav again? After that you should see _____°_____'' etc on R5K. All is explained inside the tutorials, but yiu have to read carefully. Alsomon the stick post.