Arduino undefined reference to

Robot_oct25.ino:
----------------------------------------------------------------
#include <Wire.h>
#include "armfunctions.h"
#include "defines.h"



void setup(void){
  Serial.begin(9600);

  pinMode(READMOTOR1, INPUT);
  pinMode(READMOTOR2, INPUT);
  pinMode(READMOTOR3, INPUT);
  pinMode(READMOTOR4, INPUT);
  pinMode(READMOTOR4, INPUT);
  pinMode(MOTOR1UP, OUTPUT);
  pinMode(MOTOR1DOWN, OUTPUT);
  pinMode(MOTOR2LEFT, OUTPUT);
  pinMode(MOTOR2RIGHT, OUTPUT);
  pinMode(MOTOR3IN, OUTPUT);
  pinMode(MOTOR3OUT, OUTPUT);
  pinMode(MOTOR4LEFT, OUTPUT);
  pinMode(MOTOR4RIGHT, OUTPUT);
  pinMode(MOTOR5OPEN, OUTPUT);
  pinMode(MOTOR5CLOSE, OUTPUT);
}

void loop (void){
  while (1){
      readArms();
      delay(1000);
  }
}


//
//  defines.h
//
//
//  Created by **** on 25/10/13.
//
//

#ifndef _defines_h
#define _defines_h

#define MINIMUMMOTOR1     87
#define MAXIMUMMOTOR1     1007
#define MINIMUMMOTOR2     0
#define MAXIMUMMOTOR2     1
#define MINIMUMMOTOR3     0
#define MAXIMUMMOTOR3     1
#define MINIMUMMOTOR4     0
#define MAXIMUMMOTOR4     1
#define MINIMUMMOTOR5     0
#define MAXIMUMMOTOR5     1

#define READMOTOR1  A0
#define READMOTOR2  A1
#define READMOTOR3  A2
#define READMOTOR4  A3
#define READMOTOR5  A4

#define MOTOR1UP    0   //+
#define MOTOR1DOWN  1   //-
#define MOTOR2LEFT  2   //+
#define MOTOR2RIGHT 3   //-
#define MOTOR3IN    4   //+
#define MOTOR3OUT   5   //-
#define MOTOR4LEFT  6   //+
#define MOTOR4RIGHT 7   //-
#define MOTOR5OPEN  8   //+
#define MOTOR5CLOSE 9   //-



#endif


//
//  armfunctions.h
//
//
//  Created by **** on 25/10/13.
//
//

#ifndef _armfunctions_h
#define _armfunctions_h

#include "defines.h"
#include <Arduino.h>

typedef struct{
    float motor1;
    float motor2;
    float motor3;
    float motor4;
}directions;

boolean moveArm(char, boolean, short);
void readArms(void);


#endif


//
//  armfunctions.c
//
//
//  Created by **** on 25/10/13.
//
//

#include <stdio.h>
#include "armfunctions.h"


//bool moveArm(char choise, bool direction, short time){

//}

void readArms(void){
    float motor1 = 0.0;
    int motor = 0;
    motor = analogRead(READMOTOR1);
    motor1 = (float)motor;
    motor1 = (motor1 - 87.0) * (400.0/(1007.0-87.0));

    //Serial.println(motor1);

    delay(1000);
}



Error:
Robot_oct25.cpp.o: In function `loop':
/Applications/Robot_oct25.ino:29: undefined reference to `readArms()'