While trying to establish a connection via an oracle dataadapter from within visual studio, I am getting the infamous : "ORA-12541: TNS:No Listener" msg.

I may also get the "ORA-12514:TNS:Listener does not currently know of service requested in connect descriptor"

I have allowed access to ORACLE.EXE with my mcAfee personal firewall.

I am able to TNSping my server.

The "OracleOraDb10g_home1TNSListener" windows service is Started. I've even tried restarting it.

Here is the contents of my tnsnames.ora file:

# tnsnames.ora Network Configuration File: C:\oracle\product\10.1.0\Db_1\network\admin\tnsnames.ora
# Generated by Oracle configuration tools.

ORCL =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = DBTYZQ41)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = orcl)
    )
  )

EXTPROC_CONNECTION_DATA =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC))
    )
    (CONNECT_DATA =
      (SID = PLSExtProc)
      (PRESENTATION = RO)
    )
  )

Here is the contents of my Listener.ora file:

# listener.ora Network Configuration File: C:\oracle\product\10.1.0\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\10.1.0\Db_1)
      (PROGRAM = extproc)
    )
  )

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS_LIST =
        (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC))
      )
      (ADDRESS_LIST =
        (ADDRESS = (PROTOCOL = TCP)(HOST = DBTYZQ41)(PORT = 1521))
      )
    )
  )

I'm really tearing my hair out on this one. Can someone please help me with this error.

I'm typing in "DBTYZQ41" as my server name within visual studio and entering my "SYSTEM" userid and my password which I know is correct.

I can't believe it's this hard to work with ORACLE and resolve a simple connection issue.