I will try to go into detail to see what I am missing:

Oracle has a TNSNAMES.ORA file that looks like this:

TRAC =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = medsvr)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVICE_NAME = Trac)
    )
  )

The Host = medsvr goes to the host file where the ip for the server is found.

When I create a project I add a reference to the System.data.oracleclient assembly.

I create a business object and configure the project properties to look like this:

Data Source=Trac;User ID=medselect;password=tceles

I configure the business object properties and use Oracle. It knows all the tables.

Build the partial class and everything seems ok.

This is in the program.cs SetDataSources:

ConnectionManager.AddRequiredDataSourceItem("", "SQL Connection",

DataSourceTypeOptions.SqlServer, "MyDatabase", "This connection is used by WindowsApplication1.");

// Oracle Connection

ConnectionManager.AddRequiredDataSourceItem("MedSelect", "Oracle Connection",

DataSourceTypeOptions.Oracle, "Trac", "This connection is used by WindowsApplication1.");

Just for a test I hook into the ParentFormLoading and do the following query on the Users table this business object is associated with:

FillDataTable("Select * from Users");

I build and try to run and get exception:

{"Cannot open database \"MyDatabase\" requested by the login. The login failed.\rLogin failed for user 'YOUR-72486D6880\\hp1'."}

WHAT IS GOING ON?