Problem connecting to database using Oracle.DataAccess

The DBA at my company created a new user/password for an application I am working on. I tested the login using SQL Developer and can connect to the database just fine - all the tables I have access to are there.

However, in my application, when I try to use开发者_JAVA技巧 the same credentials to connect using Oracle.DataAccess.dll, the connection fails, saying "Unhandled Exception: Oracle.DataAccess.Client.OracleException ORA-1017: invalid username/password; logon denied"

I have checked and double checked to make sure I was passing in the correct user/password. I am a bit new to Oracle, so I don't really know where to start looking for the problem. Does anyone have any ideas why this might be happening?

EDIT FOR CLARIFICATION:

The login works with my older credentials, using Oracle.DataAccess, just not with the most recent one. This is a .Net Console Application, written in C#

string conn_string = "Data Source=" + database + ";User ID=" + 
    user_id + ";Password=" + password + ";";
OracleConnection conn = new OracleConnection(conn_string);

conn.Open();

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You don't say what version of Oracle you are using. 11g does have case sensitive passwords.

Try a SQL*Net trace on the client (your PC) for the connection that works and the one that does not. Compare to see what is different.

Client Side Tracing:

Your SQLNET.ORA file should contain the following lines to produce a client side trace file:

trace_level_client = 10

trace_unique_client = on

trace_file_client = sqlnet.trc

trace_directory_client =