Trying to connect Excel 2013 with Oracle - ORA-12154

I am trying to connect MS Excel into Oracle through Data Source ODBC
and im getting error ORA-12154

When I try to connect using ODBC it works find but
when I try to connect using TNS within Excel I get the error:
Message=ORA-12154
"could not resolve the connect identifier"

how to solve it??

here it's

To clarify Hambone's response, to connect Excel to Oracle via Oracle client driver without using TNS Names:

    1.Go to Control Panel > Administrative Tools > ODBC Data Sources
    2.Go to File DSN tab
    3.Choose Oracle driver (e.g. Oracle11gr1)
    4.Provide a name for the new data source (any name)
    5.When prompted for Service Name, enter host:port/servicename e.g. db123:1521/service123