Klark DN4816U

I wanted to connect a stage box with 2 StageConnect devices (DN4888 and DN4816-I) to my PC via the Klark Teknik DN4816U. According to the specs the DN4816U should be able to power both devices. However, it does not; I had to add a power supply to the DN4888, which has to be connected directly to the DN4816U - otherwise they will not be recognised at all.
Note: the same stage box works perfectly without additional power supply when connected to the SC port of my Behringer Wing.
Apart from that, the box does what it should do. I can now use 24 inputs and 8 outputs via USB on my PC. So, I am still somewhat satisfied with my purchase.