you right! sorry, is oracle .net
pls. follow this link
http://www.connectionstrings.com/you may find the connection string u need.
a second suggestion is :
try to connect to your oracle using ODBC
Control Panel -> Administrative Tools -> Data Sources
after you seceed go to registry
HKEY_LOCAL_MACHINE\SOFTWARE\ODBC
try to locate your odbc one of the sub-keys contains the connection string.
what you've left is to copy the connection string to:
connection.ConnectionString ( ADODB.Connection )