Seems like you didn't save the file.
You can rerun the Net assistant or manually create the file and put it in the \network\admin directory; Here is a sample --

****************
orcl =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(Host = TestOra)(Port = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = orcl)
)
)


***************

You may want to provide IP Address of the server instead of the Server name in the "Host" entry if your lmhost file is not setup properly.

- Rajeev