Sparkfun CAN shield

I’ve been struggling for several weeks to get this shield to work with my Arduino Mega 2560 with almost no success. I have connected the SPI pins of the shield (10-13) to the SPI pins of the Mega (50-53). I have tried half a dozen codes and libraries, including Canduino, but the shield jus won’t send or receive. It doesn’t set an interrupt, and when I force it to read the rx0 or rx1 buffer, it sends me nonsense data. Most of the support on the web is for the specific application of reading your revs etc. from a car. I just want to read data from a sensor that uses CAN. I’m at my wits end. Either there is something basic missing in the code, some connection I need to make, maybe something to do with the speed…? I’ve been testing it with a Pcan usb converter that gives me a ‘BUSHEAVY’ error when I try sending data. Any advice would be great