CAN-BUS Sniffing

I'm hoping someone here can help. I'm trying to access the data on the CAN bus, pins 6 and 14. I purchased the CAN-BUS analyzer from Seeed

https://www.seeedstudio.com/USB-CAN-...er-p-2888.html

But it doesn't seem to work. No data is displayed even though is connects.

I have the MVP2 and VCMScanner works just fine. So why doesn't this CAN sniffer work? I've been doing a lot of reading and I keep finding comment about GM using a proprietary format. If this is true, then how did HPTuners get it?

The reason I'm doing this is to provide a custom dashboard for my kit car running a 2012 LFX 3.6L. I'm running Andriod on a raspberry PI and Realdash as the app this is displayed on an LCD screen. If HPTuners had a road-worthy app I'd use that, but they don't.

Thanks