Until those duplicates are fixed you will never get the proper results. try the following to prove it to yourself:

Table1: (no primary key)
ID - number
DateStamp - Date/Time
Desc - Text

Populate Table1 with the following:
1 01/jan/2002 texta
1 02/jan/2002 textb
2 01/feb/2002 textc
2 02/feb/2002 textd
2 03/feb/2002 texte


Create a query named qryTable1 with SQL of:

SELECT Table1.ID, Max(Table1.DateStamp) AS MaxOfDateStamp
FROM Table1
GROUP BY Table1.ID;

Create a query named qryTable2 with SQL of:

SELECT Table1.*
FROM qryTable1 INNER JOIN Tabel1 ON (qryTable1.ID = Table1.ID AND
qryTable1.MaxOfDateStamp = Table1.DateStamp);

Run qryTable2. You should have 2 rows returned showing the full record where the record is the highest date for that ID. Now open up Table1 and change the first record's dateStamp from 01/jan/2002 to 02/jan/2002. execute qryTable2 again. You now have 3 records returned even though qryTable1 only returns 2 records. This is because you are getting 1 to many results due to the duplicate dates. So until you get uniqueness in your first query, your results will be screwed in the second. Hope this helps.