Thanks for the advice Mark! Mystery solved I think.

As per your suggestion, I enabled cockpit tooltips (which only showed up for me in "windowed" mode, since I run a three-monitor display), and used the indications to tune exact frequencies for 2 NDBs that I knew were ahead of me. Once I got within 30 nm or so, the needles of the RMI (which I had set to ADF) deflected towards them.

I guess I was thrown off because I was expecing some sort of indication on the ADF panel itself, such as a centered needle on the tuning meter. There is no such indication as far as I can tell, so only the needles of the RMI indicate a successful tuning.

Is it typical for the range of the NDBs to be that short (eg. 30 nm)? That is another thing that surprised me. I guess that with a range like this, NDBs are not as useful for navigating an airliner as VORs are, unless you are lining up an approach or something.

Speaking of VORs, I also noticed that I never get any distance values appear on the DME indicator, despite the fact that I have VORs with DME capability tuned. I've only ever seen dashes. Any idea what could be going on here?

Thanks again for your help! Much appreciated!

- Bob