DS1307 with stepper motor

Other Hardware Motors, Mechanics, Power and CNC
1

Hello everyone
for my project, I have to craft an automatic pet feeder. The basic idea is that, on a specified time, a stepper motor turns to drop the food for the cats to the bowl.

I am using Arduino Uno R3, DS1307 for the RTC clock and 28BYJ-48 as my stepper motor. Stepper is controlled by ULN2003A.

Connections:
8,9,10,11 to IN1,2,3,4 of the controller;

A4 to SDA on DS1307, A5 to SCL on DS1307.

Code used:

#include <Wire.h>
#include "RTClib.h"
#include <Stepper.h>
#define STEPS 2038 // aantal stappen per één rondje

Stepper stepper(STEPS, 8,10,9,11);
RTC_DS1307 RTC; // SCL naar A5, SDA naar A4

String uur;
String uurAangepast;
String minuut;
String minuutAangepast;
String tijd;
bool roundDone = false;

void setup () {
    Serial.begin(9600);
    Wire.begin();
    RTC.begin();
  // Check to see if the RTC is keeping time.  If it is, load the time from your computer.
  if (! RTC.isrunning()) {
    Serial.println("RTC is NOT running!");
    // This will reflect the time that your sketch was compiled
    RTC.adjust(DateTime(__DATE__, __TIME__));
  }
}
void loop () {
  printTime();
  motorControl();
}

void printTime(){
  DateTime now = RTC.now(); 
    String minuut = String(now.minute());
    if(now.hour() < 10){
      uur = String(now.hour());
      uurAangepast = '0' + uur;
    }
    else{
      uurAangepast = now.hour();
    }
    Serial.print(uurAangepast);
    Serial.print(':');
    if(now.minute() < 10){
      minuut = String(now.minute());
      minuutAangepast = '0' + minuut;
    }
    else{
      minuutAangepast = now.minute();
    }
    Serial.print(minuutAangepast);
    Serial.println();
    tijd = uurAangepast + minuutAangepast;
    Serial.println(tijd);
    delay(1000);
}

void motorControl(){
   stepper.setSpeed(6); 
  stepper.step(339.6); 

  delay(3000); // wait for three second
  stepper.setSpeed(6);
  stepper.step(-339.6); 
  delay(3000);
}

Power is delivered using a breadboard.

What I do not understand is why, as soon as I plug in the RTC on pins A4 and A5, motor stops working.

Could somebody help me out please?