[AccessD] Subquery returns to many or no records

When I try to run the following query access displays the error message
subquery returned multiple records 

SELECT DISTINCT T9DATA_CATDAILYPRODM.ORAACTDT, T9DATA_CATDAILYPRODM.BOPD
FROM T9DATA_CATDAILYPRODM
WHERE (((T9DATA_CATDAILYPRODM.ORAACTDT)=#10/1/2003#) AND
((T9DATA_CATDAILYPRODM.BOPD)=(SELECT BOPD from T9DATA_CATDAILYPRODM
where USRFLD1 ="Y")) AND ((T9DATA_CATDAILYPRODM.AREADESC)="TEXAS GAS")
AND ((T9DATA_CATDAILYPRODM.SUPVNM)="TGF FORT STOCKTON" Or
(T9DATA_CATDAILYPRODM.SUPVNM)="TGF KERMIT"));

If I change the query to the following no records are returned

SELECT DISTINCT T9DATA_CATDAILYPRODM.ORAACTDT, T9DATA_CATDAILYPRODM.BOPD
FROM T9DATA_CATDAILYPRODM
WHERE (((T9DATA_CATDAILYPRODM.ORAACTDT)=#10/1/2003#) AND
((T9DATA_CATDAILYPRODM.BOPD)=(SELECT SUM(BOPD) from T9DATA_CATDAILYPRODM
where USRFLD1 ="Y")) AND ((T9DATA_CATDAILYPRODM.AREADESC)="TEXAS GAS")
AND ((T9DATA_CATDAILYPRODM.SUPVNM)="TGF FORT STOCKTON" Or
(T9DATA_CATDAILYPRODM.SUPVNM)="TGF KERMIT"));

What am I missing here. There should be records returned. Thanks

No trees were killed in the sending of this message. However a large
number of electrons were terribly inconvenienced. 



-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://databaseadvisors.com/pipermail/accessd/attachments/20031007/fce18b73/attachment.html>