Using two intensity pro but only one is working

We just got 2 intensity pro capture cards and were testing around with different cameras.

We got all our cameras working but only on one of the two cards. Both cards are detected and installed just fine. We can see the input devices in programs but one card always transmit just a black screen.

We had no time yet to test with switched cards or to try just one card but I thought I might ask here for any known problems with 2 intensity pro which can result in this behavior?

Thanks for your time.

You will need a software to work for 2 or more inputs. Try vMix