Question about HP USB-C/A Universal Dockingstation G2

Hello Community :-) I got this doc yesterday, but unfortunately I can't get a signal on the HDMI cable, the monitor just won't come on. I have also tried a very short cable or connecting the HDMI to a DP output via a display port adapter, no function. As soon as I connect it directly to the notebook, it works. I have 2 AOC (2018) monitors, neither of which turn on, starting from the docking station. They are a HP Elitebook from 2019 and a HP Dragonfly from 2020 that I used, both do not bring a picture. Thank you very much for your help and best regards, Mario