Only one instance is using this DB....coz while creation of DB i had given MAXINSTANCES 1......

am getting below error while opening DB....can any 1 let me know if i am going wrong ne where or do i have to set any thing else....or the very basic close and open wont work????????


Code:
SQL> alter database close;

Database altered.

SQL> alter database open;
alter database open
*
ERROR at line 1:
ORA-01531: a database already open by the instance


SQL> shutdown
ORA-01109: database not open


Database dismounted.
ORACLE instance shut down.
SQL>
Am confused

Abhay.