undefined is not an object (evaluating 'this.onbuffer') React Native

everyone!
while trying to show a video in my react native app I face issues, the error is:
"undefined is not an object (evaluating ‘this.onbuffer’)"

This is the code.

import * as React from ‘react’;
import { View, Text, TouchableOpacity, StyleSheet } from ‘react-native’;
import Video from ‘react-native-video’

function VideoScreen() {
return (

    <Video source={{uri: "../assets/videos/maula.mp4"}}   // Can be a URL or a local file.
        ref={(ref) => {
                 this.player = ref
               }}                                      // Store reference
               onBuffer={this.onBuffer}                // Callback when remote video is buffering
               onError={this.videoError}
                      // Callback when video cannot be loaded
           style={styles.container} />

);

}

const styles = StyleSheet.create({
container: {
position: ‘absolute’,
top: 0,
left: 0,
bottom: 0,
right: 0,
},
});

export default VideoScreen;

Can someone help me?

>Solution :

check if you’ve added this in your constructor

constructor(props) {
    super(props);
    this.onBuffer= this.onBuffer.bind(this);
  }