Database Software

HI There

I have configured Data Guard on oracle 10g (10.2.0.4) on Windows 2007 64 bits Server.
Both Primary DB and Standby DB are on same Server.

When I connect to my Primary DB, It is connected Normally as shown below.

Start --> Run --> CMD --> set oracle_sid=prmdb

c:\> sqlplus / as sysdba

SQL*Plus: Release 10.2.0.4.0 - Production on Wed Apr 17 09:48:22 2013
Copyright (c) 1982, 2007, Oracle. All Rights Reserved.
Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL>

Now Whenever I connect to my Standby DB, It connects to an Idle Instance. When I issue startup command
it displays a Message as shown below.

Start --> Run --> CMD --> set oracle_sid=stldb

c:\> sqlplus / as sysdba

SQL*Plus: Release 10.2.0.4.0 - Production on Wed Apr 17 09:48:22 2013
Copyright (c) 1982, 2007, Oracle. All Rights Reserved.

Connected to an idle instance.

SQL> startup
ORACLE instance started.

Total System Global Area 1258291200 bytes
Fixed Size 2065408 bytes
Variable Size 318770176 bytes
Database Buffers 922746880 bytes
Redo Buffers 14708736 bytes
Database mounted.
ORA-16004: backup database requires recovery
ORA-01196: file 1 is inconsistent due to a failed media recovery session
ORA-01110: data file 1: 'D:\ORACLE\ORADATA\STLDB\SYSTEM01.DBF'

Then I issue following commands to overcome this

SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE DISCONNECT
FROM SESSION;

ALTER DATABASE RECOVER MANAGED STANDBY DATABASE DISCONNECT FROM SESSION
*
ERROR at line 1:
ORA-01153: an incompatible media recovery is active

SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;

Database altered.

SQL> ALTER DATABASE OPEN;

Database altered.

What is wrong with my Standby DB?
What to do to overcome these messages Permanently?
Why Standby DB is Not connected Normally instead of I have to start it?

Regards
Thunders2777