如何访问Facebook API Java for Business帐户中的总金额

Question

我正在为我的网站创建一个analytics页面。所以我需要从facebook API获取数据。我目前的代码是

public class HelloFacebookAPI {

    public static final String ACCESS_TOKEN = [TOKEN];
    public static final long ACCOUNT_ID = [ACCOUNT_ID];
    public static final String APP_SECRET = [APP_SECRET];

    public static final APIContext context = new APIContext(ACCESS_TOKEN, APP_SECRET);
    public static void main(String[] args) {
        try {
            AdAccount account = new AdAccount(ACCOUNT_ID, context);
            System.out.println(account.getFieldAmountSpent());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

但这会一直返回null。我的帐户是商家帐户。此外，广告帐户与该帐户相关联。我怎样才能做到这一点？