Oracle Database Discussions

Hi,
I am using Windows7 and Oracle 11.2.0 version. I am trying to access oracle database by using an excel(Office 2010) macros but it is showing the following error.

Run-time error '--2147467259 (80004005)':
ORA-12454: TNS:Could not resolve the connect identifier specified

On debugging it takes to following line:-

Private Function GET_DATA(PERIOD, YEAR) As String

Dim paymenttype As String

Set cn = New ADODB.Connection
With cn
.Provider = "MSDAORA"

.Properties("Data Source").Value = "T171i0"
'"d171i0"
'"PROD"
.Properties("User ID").Value = Logon_form.Urname.Value
.Properties("Password").Value = Logon_form.Pswd.Value

--> *.Open*

On Error Resume Next

End With


Could anybody help me to solve this issue.
Some point needs to be mentioned
1. I have checked TNSNAMES.ORA and it is fine.
2. I have also checked the security permision to oracle_home folder.
3. The same macro file is working fine when I ran it in windows server 2003 and Oracle 10.
4.System DSN is properly created.

I think there is a Version Incompatibility issue.

Thanks
Anupam