Umsetzung Projekt von Uno nach Mega Board

Also ich habe ein Beispielsketch geladen - der läuft auf einen Uno.
Den gleichen Sketch auf einen Mega läuft nicht - I2C wird nicht gefunden.
Richtig angeschlossen ist es und Widerstände sind schon auf der Platine vorhanden.
Ich habe um Fehler auszuschließen den Beispielsketch direkt aus der BME280 Bibliothek genommen :

[/code

/*
 * bme280_example.ino
 * Example sketch for bme280
 *
 * Copyright (c) 2016 seeed technology inc.
 * Website    : www.seeedstudio.com
 * Author     : Lambor, CHN
 * Create Time:
 * Change Log :
 *
 * The MIT License (MIT)
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
#include "Seeed_BME280.h"
#include <Wire.h>

BME280 bme280;

void setup()
{
  Serial.begin(9600);
  if(!bme280.init()){
    Serial.println("Device error!");
  }
}

void loop()
{
  float pressure;
  
  //get and print temperatures
  Serial.print("Temp: ");
  Serial.print(bme280.getTemperature());
  Serial.println("°C");//The unit for  Celsius because original arduino don't support speical symbols
  
  //get and print atmospheric pressure data
  Serial.print("Pressure: ");
  Serial.print(pressure = bme280.getPressure());
  Serial.println("Pa");

  //get and print altitude data
  Serial.print("Altitude: ");
  Serial.print(bme280.calcAltitude(pressure));
  Serial.println("m");

  //get and print humidity data
  Serial.print("Humidity: ");
  Serial.print(bme280.getHumidity());
  Serial.println("%");

  delay(1000);
}