More groups resulting from sql query than expected

When I run query1 below I get a sum of amounts paid for every district for the month of April 2002 as shown in result1.  

However, when I make the minor change of including payment adjustments as in query2, I get multiple sums for those districts that adjustment transactions occurred.  My intention is to add up the total transaction amount for each district for the month.  Therefore I expected the same amount of sums as in the first query.

Where did I go wrong?

query1:
select
    (-1 * sum(AMOUNT_PAID)), last_day(payment_date), district
from
     ncharge_pay, ntitle, nparcel
where
     ncharge_pay.tran_details = 'PAYMENT'   and
     ntitle.title_sn = ncharge_pay.title_sn and
     nparcel.parcel_sn = ntitle.parcel_sn and
     payment_date between '01-apr-02' and '30-apr-02' and      
     nparcel.section is not null
group by
     last_day(ncharge_pay.payment_date), nparcel.district

result1:
(-1*SUM(AM     LAST_DAY(PAYMENT_DAT DI
---------- -------------------- --
  10971.17      30-APR-02                            BZ
29178.9824     30-APR-02                           CY
45502.8486     30-APR-02                           CZ
 37726.368      30-APR-02                           OW
     13400        30-APR-02                           SC
      1250         30-APR-02                           TO


query2:
select
    (-1 * sum(AMOUNT_PAID)), last_day(payment_date), section
from
     ncharge_pay, ntitle, nparcel
where
     (ncharge_pay.tran_details = 'PAYMENT' or ncharge_pay.tran_details = 'PAYMENT ADJUSTMENT'  or ncharge_pay.tran_details = 'TAX PAYMENT ADJ.' or ncharge_pay.tran_details = 'TAX PAYMENT ADJUSTMENT') and
     ntitle.title_sn = ncharge_pay.title_sn and
     nparcel.parcel_sn = ntitle.parcel_sn and
     payment_date between '01-apr-02' and '30-apr-02' and
     nparcel.section is not null
group by
     last_day(ncharge_pay.payment_date), nparcel.section

result2:
(-1*SUM(AM LAST_DAY(PAYMENT_DAT DI
---------- -------------------- --
   5830.28      30-APR-07            BZ
   27427.7      30-APR-07            CY
118751.036    30-APR-07            CZ
  19257.85     30-APR-07            OW
   9882.82      30-APR-07            SC
    271.45       30-APR-07            TO
     -5043       30-APR-07            CZ
      -372        30-APR-07            SC
    -48.51       30-APR-07            CZ
      -144        30-APR-07            OW
    -302.3       30-APR-07            OW
    -110.5       30-APR-07            OW
12 rows selected.