New to Marlin: RAMPS heated bed not working (2 replies)

Just changed over to Marlin (1.1.3) from Repetier on my RAMPS printer as I wanted to try the bed levelling, and can't seem to get the heated bed to power on. The temp reading for the bed works. Bed is plugged in to D8. Don't think it's an electrical issue as if I reflash the board with Repetier the heated bed works fine. Relevant Marlin settings below:-

#define MOTHERBOARD BOARD_RAMPS_14_EFB
#define TEMP_SENSOR_BED 11
//#define PIDTEMPBED
#define BED_LIMIT_SWITCHING
#define MAX_BED_POWER 255

Scratching my head on this one. Any help would be appreciated!