checkbox is not displaying checked (react native)

I am using checkbox from react-native-element

When i check the box it dose not display checked how can i display it ? here is my code

 <View>
                    <FlatList data={all_national_number}
                        keyExtractor={(item, index) => index.toString()}
                        renderItem={({ item }) =>
                            <CheckBox

                                title={item} 
                                uncheckedIcon={<Image source={require('../../assets/unchecked.png')} />}
                           checkedIcon={<Image source={require('../../assets/checked.jpg')} />}

                                onPress={() => this._onSelect(item)}>
                            </CheckBox>

                        }>
                    </FlatList>