dblink not returning result

I am using Postgresql 9.1. I found that dblink is not returning result for BEGIN transaction.


------------------------------------------------------------
select new_conn('conn1');
select new_conn('conn2');

select dblink_send_query('conn1','begin;  update t2 set i=10 where nam=''a1'';');
select dblink_send_query('conn2','begin;  delete from t2 where nam=''a1'';');

pgdb=# select * from lock_vw;
 datname | relname | transactionid |       mode       | granted | usename  |         current_query          |          query_start          |       age       | procpid
---------+---------+---------------+------------------+---------+----------+--------------------------------+-------------------------------+-----------------+---------
 pgdb    | t2      |               | RowExclusiveLock | t       | postgres | <IDLE> in transaction          | 2011-11-03 12:26:17.175681+06 | 00:00:04.05115  |    9414
 pgdb    | t2      |               | ExclusiveLock    | t       | postgres | begin;  delete from t2 where n | 2011-11-03 12:26:17.180294+06 | 00:00:04.046537 |    9415
 pgdb    | t2      |               | RowExclusiveLock | t       | postgres | begin;  delete from t2 where n | 2011-11-03 12:26:17.180294+06 | 00:00:04.046537 |    9415
(3 rows)


select dblink_send_query('conn1','select i,nam from t2')

select * from dblink_get_result('conn1') as t2(i int, nam text);
ERROR:  function return row and query-specified return row do not match
DETAIL:  Returned row contains 1 attribute, but query expects 2.
select dblink_send_query('conn2','rollback');

-- Supposed to send result here
pgdb=# select * from dblink_get_result('conn1') as t2(i int, nam text);
 i | nam
---+-----
(0 rows)

pgdb=# select * from t2;
 i |  nam 
---+-------
 1 | asdas
 2 | a1
(2 rows)
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Could any one please tell me why?