CAN BUS Problem Receiving with Serial

did you connect your cluster to the ElecFreaks CAN BUS Shield D type connector or to the screw terminals?
if you connected to the 9 pin Dtype connector looking at the schematic the ElecFreaks CAN BUS Shield the pin out is CAN high is pin 3 and CAN low is pin 5

on all my other canbus kit the pin out is CAN low is pin 2 and CAN high is pin 7 with CAN_GND pin 3

I would recommend you get a USB-CAN dongle for a PC so you can check that the ElecFreaks CAN BUS Shield is working correctly