Cannot connect to Database after install Developer Suite

Question

Help..
I installed Oracle Database and everything seems work properly. I can connect to the database. (system/oracle@orcl)
well, but after I install the developer suite, I can't connect to the database anymore.
I did check the services and both OracleOraDb10g_home1TNSListener and OracleServiceORCL are started.
I try to search help from google but I cannot solve the problem by myself. I also include two ora file below,
tnsnames.ora
=====
# tnsnames.ora Network Configuration File: C:\oracle\product\10.2.0\db_1\network\admin\tnsnames.ora
# Generated by Oracle configuration tools.
ORCL =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = orcl)
EXTPROC_CONNECTION_DATA =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
(CONNECT_DATA =
(SID = PLSExtProc)
(PRESENTATION = RO)
====
listener.ora
===
# listener.ora Network Configuration File: C:\oracle\product\10.2.0\db_1\network\admin\listener.ora
# Generated by Oracle configuration tools.
SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(SID_NAME = PLSExtProc)
(ORACLE_HOME = C:\oracle\product\10.2.0\db_1)
(PROGRAM = extproc)
LISTENER =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
(ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
====
everything seems should working properly but I still have problem cannot connect to the database. SQLPlus says "ORA-12154" and "ORA-12514"
please help me.. I need to finish my project within next 2 weeks or I have to study one more year. T_T

Answer 1

Hi ...
The Oracle Doc points out as actions in this type of error:
- If you are using local naming (TNSNAMES.ORA file):
- Make sure that "TNSNAMES" is listed as one of the values of the NAMES.DIRECTORY_PATH parameter in the Oracle Net profile (SQLNET.ORA)
- Verify that a TNSNAMES.ORA file exists and is in the proper directory and is accessible.
- Check that the net service name used as the connect identifier exists in the TNSNAMES.ORA file.
- Make sure there are no syntax errors anywhere in the TNSNAMES.ORA file. Look for unmatched parentheses or stray characters. Errors in a TNSNAMES.ORA file may make it unusable.
- If you are using directory naming:
- Verify that "LDAP" is listed as one of the values of the NAMES.DIRETORY_PATH parameter in the Oracle Net profile (SQLNET.ORA).
- Verify that the LDAP directory server is up and that it is accessible.
- Verify that the net service name or database name used as the connect identifier is configured in the directory.
- Verify that the default context being used is correct by specifying a fully qualified net service name or a full LDAP DN as the connect identifier
- If you are using easy connect naming:
- Verify that "EZCONNECT" is listed as one of the values of the NAMES.DIRETORY_PATH parameter in the Oracle Net profile (SQLNET.ORA).
- Make sure the host, port and service name specified are correct.
- Try enclosing the connect identifier in quote marks. See the Oracle Net Services Administrators Guide or the Oracle operating system specific guide for more information on naming.According to the above and my LISTENER settings in listener.ora file which is...
LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = myhost)(PORT = 1521))
  )there is one ')' missing closing parenthesis....
So , modify your LISTENER settings ... according to the below....The difference is the ')' in bold....
LISTENER =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
(ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
Can you connect now.....????
Regards,
Simon