ORA-14274: partitions being merged are not adjacent?

Hello Team,
I am testing Merge functionality in Oracle Partitioning on 11.2/OEL

I have created a Table - partition by range - every 10 minutes.

1)
CREATE TABLE s_sales
(
sales_amt number
,d_date_dtt date)
partition by range (d_date_dtt)
interval(numtodsinterval(10,'minute'))
store in (p1_tbsp,p2_tbsp)
(partition p1 values less than (to_date('01-10-2013','dd-mm-yyyy'))
)
/

2)
I have inserted 4 rows - each @ 10 minutes.

select * from s_sales;

 SALES_AMT D_DATE_DTT
---------- -------------------
        90 07/11/2013 16:33:43
         1 10/04/2013 15:35:35
         2 10/04/2013 16:00:57
        99 10/09/2013 15:09:55


3) metadata looks fine.

 select table_name, partition_name, partition_position part_pos
  ,interval, tablespace_name, high_value
  from user_tab_partitions