Unable to work with ODAC, VS2008 and Oracle Database 10g XE

Question

I have downloaded and installed ODAC 11.1.0.6.21. I have followed the instructions in the 2 Day + .Net Developer's Guide (Chapter 3 - Building a Simple .NET Application Using ODP.NET) until I got to adding reference: when I added the Oracle.DataAccess 2.111.6.20, I observed that the new Refererence did not appear in Solution Explorer as described in the Guide.
However I continued with the steps until I got to the testing phase, ran the form and entered Hr for User Id, Hr for Password and XE for data Source as I am running Oracle 10g XE. I got this error with every attempt: ORA-12154: TNS:could not resolve the connect identifier specified.
From Server Explorer however, I can connect and see Schema Objects but when I right click Packages for eg, to create a procedure that uses a Ref Cursor I see only Refresh and Properties in the corresponding context menu, no New Package link!
What could be the cause of all these?
1. Is XE my correct Data Source?
2. Why is the new Reference not visible in my solution explorer?
3. Is my VS2008 or ODAC not configured/Installed Correctly?

Answer 1

The tnsnames.ora file seem to be auto configured. However I tried updating it with Notepad when I changed my computer name to no avail. I had to revert back to my old computer name.
This is the content of my tnsnames.ora:
XE =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = obinna)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = XE)
EXTPROC_CONNECTION_DATA =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC_FOR_XE))
(CONNECT_DATA =
(SID = PLSExtProc)
(PRESENTATION = RO)
ORACLR_CONNECTION_DATA =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC_FOR_XE))
(CONNECT_DATA =
(SID = CLRExtProc)
(PRESENTATION = RO)
Please if there is any clause that need to be changed point it out for me.
Thanks for your reply.