Arduino - no puedo activar los relays

#include <Filters.h>

float testFrequency = 60;                     // Frecuencia (Hz)

float windowLength = 40.0/testFrequency;     // promedio de la señal

#include <Wire.h>

int Sensor = 0; //A0

int Relay1 = 13;

int Relay2 = 10;

int Relay3 = 11;

float intercept = -0.04; // to be adjusted based on calibration testing

float slope = 0.0405; // to be adjusted based on calibration testing

float volts; // Voltage

unsigned long periodo = 1000;

unsigned long tiempoAnterior = 0;

void setup() {

  Serial.begin(9600);

  pinMode (Relay1 , OUTPUT); // salida relay1

  pinMode (Relay2 , OUTPUT);  //salida relay2

  pinMode (Relay3 , OUTPUT); //salida relay3

}

void loop() {

  RunningStatistics inputStats;

  inputStats.setWindowSecs(windowLength);

  while(true) {

    Sensor = analogRead(A0);  //Leer pin Analógico

    inputStats.input(Sensor);

    if((unsigned long)(millis() - tiempoAnterior) >= periodo) {

      volts = intercept + slope * inputStats.sigma(); //offset y amplitud

      volts = volts*(40.3231);                        //calibración

      Serial.print("\tVoltage: ");

      Serial.println(volts);

      tiempoAnterior = millis();

      if ((float) volts>5);

      digitalWrite (Relay1 , HIGH);

      if (volts >5<33);

      digitalWrite (Relay2 , HIGH);

      if (volts >34<70);

      digitalWrite (Relay3 , HIGH);

      digitalWrite (Relay2 , LOW);

      if (volts >71<133);

      digitalWrite (Relay3 , HIGH);

      digitalWrite (Relay2 , HIGH);

    }

  }

}