当我在片段Java类中初始化youtubesupportfragment时，它在以下代码行中给我错误：

youtubePlayerFragment = (YouTubePlayerSupportFragment) getactivity().getSupportFragmentManager()
                .findFragmentById(R.id.frame_fragment);

youtubePlayerFragment.initialize（YouTubeAPIKey，onInitializedListener）;

        if (model.getNextPageToken() == null) {
            isLastPage = true;
        }

这两行我都出现了错误

请帮助我如何解决

这是错误

尝试在空对象引用上调用虚拟方法'void com.google.android.youtube.player.YouTubePlayerSupportFragment.initialize（java.lang.String，com.google.android.youtube.player.YouTubePlayer $ OnInitializedListener）'