connection error to oracle with ado.net

Hi!
I try to connect from c# to oracle 9.2 but i get this error:
System.Data.OleDb.OleDbException: Oracle error occured, but error message could not be retrieved from oracle.
There is no sqlnet.log created.
How to solve this?
Thanks for your answer!
[295 byte] By [blacib] at [2007-11-19 3:18:42]
# 1 Re: connection error to oracle with ado.net
Maybe ConnectionString is error!
jjrabbit at 2007-11-10 3:30:57 >