escsdksample报错

public void sample() {
        DescribeInstancesRequest describe = new DescribeInstancesRequest();
        IClientProfile profile
        = DefaultProfile.getProfile("cn-hangzhou", "<your accessKey>",
        "<your accessSecret>");
        IAcsClient client = new DefaultAcsClient(profile);
        try {
                DescribeInstancesResponse response
                = client.getAcsResponse(describe);
        }catch (ServerException e) {
                e.printStackTrace();
        }
        catch (ClientException e) {
                e.printStackTrace();
        }
}

这个例子是不是还需要添加有其他的代码啊？我把"<your accessKey>", "<your accessSecret>"替换为我自己的怎么报错呢。
错误信息：
com.aliyuncs.exceptions.ClientException: IncompleteSignature : The request signature does not conform to Aliyun standards.