My next step (before driver stuff) would be to figure out where in the chain you are having issues.
(1) check if the camera is working on its own (assuming it can record to internal memory or something). No? Time to troubleshoot the camera.
(2) connect from the camera’s mini hdmi to a tv/monitor and see if you’re getting a picture. No? Time to troubleshoot the hdmi out or hdmi cable.
- plug some other hdmi source into the capture card. Does it work? No? Problem is probably with the capture card/computer.
Congrats!