VU-meter not working for Rack Instrument

I use Groove Agent 4 and Halion SE as a rack-instrument.
When i play my project i hear what these instuments are doing and can see my master-output has signal because of the stereo VU-meter.
I can adjust the volume of the instrument-channels in the mixer but the VU-meters don’t show anything, the just stay black.

What can i do to get the VU-meters of these rack-instruments running/working?

Hi,

Could you please attach a screenshot? I’m not sure, I understand 100% which meters can you see, and which you can’t see. Thanks.