Can't Compile

[kevidoplz]

I am using an Arduino lenonardo and when i compile the sketch, it gives me and error:
Arduino: 1.9.0-beta (Windows 10), Board: "Arduino Leonardo"

Build options changed, rebuilding all
C:\Users\kevin\AppData\Local\Temp\ccMDCXOx.ltrans0.ltrans.o: In function `CapacitiveKey::keyUpdate(bool)':

sketch/CapacitiveKey.h:23: undefined reference to `CapacitiveSensor::capacitiveSensorRaw(unsigned char)'

C:\Users\kevin\AppData\Local\Temp\ccMDCXOx.ltrans1.ltrans.o: In function `__base_ctor ':

sketch/CapacitiveKey.h:13: undefined reference to `CapacitiveSensor::CapacitiveSensor(unsigned char, unsigned char)'

sketch/CapacitiveKey.h:13: undefined reference to `CapacitiveSensor::CapacitiveSensor(unsigned char, unsigned char)'

collect2.exe: error: ld returned 1 exit status

exit status 1
Error compiling for board Arduino Leonardo.

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

[kevidoplz]

The code is :

#include "CapacitiveSensor.h"
#include <Keyboard.h>

#include "CapacitiveKey.h"

//#define SERIAL_OUTPUT
#define DISABLE_PIN 15

void setup() {
#ifdef SERIAL_OUTPUT
Serial.begin(115200);
#endif
Keyboard.begin();
pinMode(DISABLE_PIN, INPUT_PULLUP);
}

CapacitiveKey key0 = CapacitiveKey(
2, //Capacitive Send Pin
7, //Capacitive Sense Pin
6, //LED Pin
6, //Capacitive Treshold
'z', //Keyboard Key
255 //LED Brightness (0-255)
);
CapacitiveKey key1 = CapacitiveKey(
4, //Capacitive Send Pin
8, //Capacitive Sense Pin
10, //LED Pin
5, //Capacitive Treshold
'x', //Keyboard Key
255 //LED Brightness (0-255)
);

void loop() {
bool keyboardActive = digitalRead(DISABLE_PIN);
key0.keyUpdate(keyboardActive);
key1.keyUpdate(keyboardActive);

#ifdef SERIAL_OUTPUT
Serial.print(key0.sample);
Serial.print(",");
Serial.println(key1.sample);
#endif
}

[Fexooo]

Have you installed the CapacitiveSensor Library in your Arduino IDE?
After I installed that it compiled without a problem!