i am creating connection string for oracle in c#

below is my code 

```
 OracleConnection cn = new OracleConnection("Data Source=(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=192.168.0.5 )(PORT=1521)))(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=ORCL)));User Id=nTireoffice ;Password=nTireoffice;");
        DataTable dt = new DataTable();
        string strSql = " select to_number (nvl(max(nvl(Region_ID ,0)),0)+1 ) as No from BO_REGION_MASTER ;";

        cn.Open();

        OracleDataAdapter objSda = new OracleDataAdapter(strSql, cn);

        objSda.Fill(dt);
        string s = dt.Rows[0][0].ToString();

```

its throwing exception ORA-06413: Connection not open. 

i am using windows 8 enterprises 64 bit os

thank u...