rd_kafka_offsets_for_times return offset -1

[eaglebrothers]

                            int patition_num = 3;
                            struct timeval ddnow;
                            gettimeofday(&ddnow, NULL);
                            long int li = (ddnow.tv_sec - 3600*7) * 1000;
                            rd_kafka_topic_partition_list_t *subscription = rd_kafka_topic_partition_list_new(1);
                            rd_kafka_topic_partition_list_add(subscription, topic, patition_num)->offset=li;

                            err = rd_kafka_offsets_for_times(rk, subscription, 10000);
                            if (err != RD_KAFKA_RESP_ERR_NO_ERROR) {
                                    fprintf(stderr, "OFT ERROR: %s\n", rd_kafka_err2str(err));
                            }        
                            printf("offset new :%ld\n", (subscription->elems)->offset);
                            rd_kafka_topic_partition_t *tp = rd_kafka_topic_partition_list_find(subscription, topic, patition_num);
                            fprintf(stdout, "OFF new %s/%d: %ld err:%d:\n", tp->topic, tp->partition, tp->offset, tp->err);

change some timestamp in "li"
return offset is -1

set li = RD_KAFKA_OFFSET_END or RD_KAFKA_OFFSET_BEGINNING
return offset is ok