Making vehicle stop in front of wall using stepper motor and ultrasonic (HELP)

Projects General Guidance
20

I've done some testing and trying out different methods, this seems to be the way to go. The motors turn on but nothing happens...what did i miss?

const int TRIGPIN = 7; // sonar pins
const int ECHOPIN = 6;
const int Motor_Left_Direction = 3; //motor pins
const int Motor_Right_Direction = 5;
const int Motor_Left_Rotate = 2;
const int Motor_Right_Rotate = 4;


long duur, distance;
int flag = LOW;
int sensorFlag = 0;
int currentmillis = 0;
int previousmillis = 0;
int delaytime = 65;

void setup() {

  pinMode (TRIGPIN, OUTPUT); //pinmodes
  pinMode (ECHOPIN, INPUT);
  pinMode (Motor_Left_Direction, OUTPUT);
  pinMode (Motor_Right_Direction, OUTPUT);
  pinMode (Motor_Left_Rotate, OUTPUT);
  pinMode (Motor_Right_Direction, OUTPUT);
  Serial.begin(9600);
  
}

void loop() {
  SonarSensor(TRIGPIN,ECHOPIN);
  if (distance >100) //als afstand groter dan 10 cm -> forwarddriving
  {
   forwarddriving();
  }
  if (distance <=100) //als afstand groter of gelijk aan 10 cm, doe niks = STOP
  {

  }
}

void SonarSensor(int TRIGPIN, int ECHOPIN){
  sensorFlag = flag;
  if (sensorFlag == HIGH)
  {

  digitalWrite (TRIGPIN, LOW); //code van standaard sonar uit blackboard
  delayMicroseconds (100);
  digitalWrite (TRIGPIN, HIGH);
  delayMicroseconds (100);
  digitalWrite (TRIGPIN, LOW);
  duur = pulseIn(ECHOPIN, HIGH); //kijk hoelang puls is
  distance = (duur/2)/29,1;
  Serial.println(distance);
  
  }
 }

void forwarddriving()
{
  digitalWrite(Motor_Left_Direction, LOW); //aanstellen welke kant de motoren opdraaien
  digitalWrite(Motor_Right_Direction, HIGH);

  digitalWrite(Motor_Left_Rotate, HIGH); //pulsen sturen naar de hoogte van delaytime uit if statements
  digitalWrite(Motor_Right_Rotate, HIGH);
  delayMicroseconds(1000);
  digitalWrite(Motor_Left_Rotate, LOW);
  digitalWrite(Motor_Right_Rotate, LOW);
  delayMicroseconds(1000);  
}

int timing(int delaytime)
{
    currentmillis = millis();
    if (currentmillis - previousmillis >= delaytime)
    {
      previousmillis = currentmillis;
      flag = HIGH;
    }
   else
   {
    flag = LOW;
   }
   return flag;
}

thanks in advance