Hi Michel,

My Database name is ORDTRACK and Service Name is actdat.
If i need to export, I usually login using: system/manager@actdat
i.e.

c:\>exp

Export : Release 8.1.7.0.0 - Production on Wed Jun 9 16:17:53 2010

(c) copyright 2000 oracle corporation. All rights reserved.

username: system/manager@actdat

EXP-00056: Oracle error 1017 encountered 
ORA-01017: Invalid username/password; logon denied


----------------------------------------------------------

If i try connecting using system/manager without specifying the conection string it is accepting. But the problem is that when i try to export not all the tables in my database are being exported. 

Also if I connect to SQL Plus without specifying the Host string, I am able to connect. I type Username as 'system' and Password as 'manager'.


--------------------------------------------------------------

This is my tnsnames.ora file in the Client machine 

# TNSNAMES.ORA Network Configuration File: D:\oracle\ora81\network\admin\tnsnames.ora
# Generated by Oracle configuration tools.

INST1_HTTP =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.116)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVER = SHARED)
      (SERVICE_NAME = actdat)
      (PRESENTATION = http://admin)
    )
  )

actdat =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 195.202.94.59)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVICE_NAME = ordtrack)
    )
  )

testprod =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.116)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVICE_NAME = testprod)
    )
  )

test =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.45)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVICE_NAME = test)
    )
  )

---------------------------------------------------------------

This is also my tnsnames.ora file in the Server

# TNSNAMES.ORA Network Configuration File: F:\oracle\ora81\network\admin\tnsnames.ora
# Generated by Oracle configuration tools.

ORDTRACK =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = server)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVICE_NAME = Ordtrack)
    )
  )

INST1_HTTP =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = server)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVER = SHARED)
      (SERVICE_NAME = Ordtrack)
      (PRESENTATION = http://admin)
    )
  )

EXTPROC_CONNECTION_DATA =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC0))
    )
    (CONNECT_DATA =
      (SID = PLSExtProc)
      (PRESENTATION = RO)
    )
  )

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Any kind of help will be appreciated.
Rgds
Obwaka.