ORA-03135: connection lost contact

Hi, 1)    I executed the following comand on primary to create standby database. 

ALTER DATABASE ADD STANDBY LOGFILE .....

2) When I ran DG_phy_stby_diag.sql on standby database I got the following error:

SQL>
SQL> -- Determine if any error conditions have been reached by querying thev$dataguard_status
SQL> -- view (view only available in 9.2.0 and above):
SQL>
SQL> column message format a80
SQL> select message, timestamp
  2  from v$dataguard_status
  3  where severity in ('Error','Fatal')
  4  order by timestamp;

MESSAGE                                                                          TIMESTAMP
-------------------------------------------------------------------------------- -------------------------
RFS[2]: Unable to open standby log 4: 313                                        10ÔÂ-12-2009 09:09:42
RFS[1]: Unable to open standby log 7: 313                                        10ÔÂ-12-2009 09:09:42