Left join query in ADO gives FALSE instead of NULL from linked sqlserver

(previously posted in .formscoding group but got no responses)

Hi,
I have been using DAO and ADO for years to get at data from linked tables
and by accident I am finding a fault with ADO.

My query is below and tmpTrans is a local Access table while all the
others
are SQL2005 tables.  I am linked to all of them.

If I use     DAO - Set rsMembers = CurrentDb.OpenRecordset(strSQL,
dbOpenDynaset, dbSeeChanges, dbReadOnly)
and get   0001           1             28921.71     False          0
                0003           1             0.14             Null
Null

If I use   ADO - rsMembers.Open strSQL, CurrentProject.Connection,
adOpenForwardOnly, adLockReadOnly, adCmdText
and get   0001           1             28921.71     False          0
                0003           1             0.14             False
Null                       ' which is WRONG !!!!!!!!!! False should be
Null

SELECT tblMembers.AcNo,
                tmpTrans.AcTyp, tmpTrans.Balance,
                tblOver70Bals.Covered, tblOver70Bals.ShareBal,
FROM (tblMembers LEFT JOIN tblOver70Bals ON tblMembers.AcNo =
tblOver70Bals.AcNo) INNER JOIN tmpTrans ON tblMembers.AcNo = tmpTrans.AcNo
WHERE  (tblMembers.AcOpen <> 0)
ORDER BY tmpTrans.AcTyp, tmpTrans.AcNo;

Can anyone explain please?
Any solution?  I prefer ADO.
I may now have to go back and review mounds and mounds of queries.

Thanks
Brian