I haven't been able to make istop motion to recognise my camcorder, help please!

I have a HD Panasonic SD900. It’s the same camcorder I used during an animation course I took months ago using istopmotion and a mac. So, i know it should work but I don’t know how. I’m trying to connect the panasonic camcorder to the macbook pro retina using the hmdi port. Istopmotion seems not to recognise the camera. I have tried to run quicktime to recognise the camera but the only camera it recognises is the built-in. I have also tried to connect the camcorder to a blackmagic intensity extreme box with an hmdi cable and from the blackmagic to the macbook pro retina with the correct thunderbolt cable but still it doesn’t work. Can anyone help please?