Arduino with MAVlink and FastSerial error

Hi all,

Has anyone got any experience using MAVlink and therefore FastSerial on Arduino?

I've got an odd linking error, where it's not liking "Serial.begin(57600);".

source071211.cpp.o: In function `setup':
C:\Users\Simon\AppData\Local\Temp\build7399018532809904204.tmp/source071211.cpp:102: undefined reference to `FastSerial::begin(long)'

Any ideas from anyone who's done this before?

Crossposted.

Yep, because it's a programming error and a comms error so helpful to two groups of onlookers.

Any ideas??