How to link Master-Detail relation?

I'm new to Delphi and trying to link two tables on two fields (a composite
key).  II'm using DBASE(IDAPI) driver.  I can link tables on one single
field.  The documentation said that you can link two fields too.  If I use
ODBC to access Dbase tables, I can easily do that.  But I'm using the
dBase driver, the index I created is on two fields.  When I bring up the
'Field Link Designer', and choose the index name, nothing shows up in the
'Detail Fields' list box.

I really appreciate any help or information. Thank you.