Problem with functionsetBrightness()

Hello I am trying to use the functions of the mbed adafruit library but the one to change the brightness of the leds or return the color to use is causing me problems.
Can you help me ?

/* mbed Microcontroller Library

  • Copyright © 2019 ARM Limited
  • SPDX-License-Identifier: Apache-2.0
    */

#include “mbed.h”
#include “platform/mbed_thread.h”
#include “DotStar.h”
#include “SPI.h”
#define numLEDs 32 // Number of LEDs in strip
// Here’s how to control the LEDs from any two pins:
#define dataPin PB_5
#define clockPin PB_3
#define miso_ PB_4

#define tempo 100
// Blinking rate in milliseconds
#define BLINKING_RATE_MS TA/8
#define Perimetre 2.07
int main()
{
Adafruit_DotStar strip(numLEDs, miso_, dataPin, clockPin, 8000000 ,DOTSTAR_BRG) ;
signed short ILS=0;
signed short vitesse=0;
signed short TT= (Perimetre/vitesse)1000 ;// on multiplie par 1000 pour mettre le temps en ms.
signed short TA=TT/4; // car on veut afficher seulement sur les ¼ supérieur de la roue.
signed short B;
signed short G;
signed short R;
Timer t;
while (true)
{
strip.begin();
for (int i=0; i < 30; i++)
{
B=i
55;
R=i6;
G=i
20;
thread_sleep_for(tempo);
strip.setBrightness(64);
strip.setPixelColor(i, B, R, G);
strip.show();
}
}
}
Error: L6218E: Undefined symbol Adafruit_DotStar::numPixels() (referred from …/…/build/main.NUCLEO_L432KC.o).