Setup Marlin Firmware for Diamond 3 color extruder showing errors

Dear respected sir, I am getting errors whenever I do some modification of Marlin firmware for Diamond extruder. I am using RUMBA board.
Here is some of my modification,
#define MOTHERBOARD BOARD_RUMBA

Enable, #define SINGLENOZZLE as Diamond nozzle has single nozzle.

There are 3 stepper for 3 extruder and that's why I have done following modification
#define MIXING_EXTRUDER
#if ENABLED(MIXING_EXTRUDER)
#define MIXING_STEPPERS 3 // Number of steppers in your mixing extruder
#define MIXING_VIRTUAL_TOOLS 16 // Use the Virtual Tool method with M163 and M164
//#define DIRECT_MIXING_IN_G1 // Allow ABCDHI mix factors in G1 movement commands
#endif

But when compile the firmware, then it shows some errors
" exit status 1
#error "MIXING_EXTRUDER currently only supports one extruder."

But I do not know why such errors showing.

Edited 2 time(s). Last edit at 03/30/2018 12:33AM by mubarak111nsu.

you need

#define EXTRUDERS 1

as there is only one extruder.

OLA senhores estou encontrando o mesmos problema .
esta e a minha configuração:

// This defines the number of extruders
// :[1, 2, 3, 4, 5]
#define EXTRUDERS 1

// For Cyclops or any "multi-extruder" that shares a single nozzle.
#define SINGLENOZZLE

#define MIXING_EXTRUDER
#if ENABLED(MIXING_EXTRUDER)
#define MIXING_STEPPERS 3 // Number of steppers in your mixing extruder
#define MIXING_VIRTUAL_TOOLS 16 // Use the Virtual Tool method with M163 and M164
//#define DIRECT_MIXING_IN_G1 // Allow ABCDHI mix factors in G1 movement commands
#endif


E MESMO ASSIM APARECE ESTE ERRO:

exit status 1
#error "SINGLENOZZLE requires 2 or more EXTRUDERS."