If you are facing the choice of e.g. Access via DDE, Access via OLEDB,
Access via ODBC, all of the choices may work but
a. each method may also fail, in which case you will probably have to try
the other methods. Generally speaking DDE will work with most tables and
queries, but not if the database has been secured. The other methods will
not let you use parameter queries or user-defined Access VBA functions.
b. each method has its own consequences. For example, if you connect via
DDE, Access will start which may have consequences for the reliability of
whatever you are doing. If you connect using ODBC, whole numbers suchas 1234
may appear as 1234.0, and dates may appear in ISO-type formats.
If you are going into the New Data Source dialog, you are probably doing the
wrong thing and should instead locate and select the .mdb and use the Open
button. However, if you are not using a .mdb let us know what you are
attempting.