I called the support and got help yesterday and the day before that (45 minutes + 30 minutes).
Here's the fix: 1. Connect the "extender" to the computer. (Make sure the computer recognises the extender: you should see a "Human Interface Device" under "Control panel", System, Hardware, "Device manager") 2. Start the "Logitech Harmony Remote" software (either the local or through the Harmony website). 3. Select "connectivity" at the top of the window. 4. Are both the remote and the extender listed? If not: add the missing unit. 5. Update the firmware in the extender. (follow the instructions) 6. Update the firmware in remote. (follow the instructions) 7. Add devices, activities and voila, it works! At least it does for me!
Note. Do not update the "Logitech Harmony Remote" software! The version you get then will not work (according to me and the support verfied this also), and it seems to cause a java error to the version supplied on the CD coming with the Harmony. The java error remains even if you uninstall the "update version". The support said (yesterday) they are working on new software and documentation. (Maybe the should have done that a few months ago or so ...)
One good thing: I did find the Logitech support to be most helpful and kind!
