Field Update Using DSUM: Field Joins Are Not Working Correctly

I know there are numerous threads regarding dsum() on the forum, but I wasn't able to find the exact answer to my problem.

The root of my problem is that I'm trying to update a field on a table using dsum, which references another query to update the table. Although I have all of the correct keys from the physical table joined to the query in the dsum function, the code/ms access seems to ignore the joins. As a result, all payees are having their "vol" field set instead of a select subset.

Query (GetTxnVolAmtTR"):

SELECT p.payee_id, sum(txn_volume) AS vol, t.market, t.period_id
FROM ft_payees AS p, ft_txn_summary AS t
WHERE p.payee_id=t.payee_id And p.market=t.market
GROUP BY t.payee_id, t.period_id, t.market, p.payee_id;


Update statement (references the query above):

UPDATE tmp_ft_component AS rc
SET rc.volume = Dsum("vol","GetTxnVolAmtTR","GetTxnVolAmtTR.payee_id= " & [rc.payee_id] And "GetTxnVolAmtTR.market= " & [rc.market] And "GetTxnVolAmtTR.period_id= " & [rc.period_id] & "")
WHERE rc.component_name='Total Revenue';

as you can see, I have all of the fields I want joined, but the code seems to ignore this. I've tried looking at this site: http://www.mvps.org/access/general/gen0018.htm , but haven't found my answer. Any help would be much appreciated!