SQL & PL/SQL :: Trigger For Updating Two Accounts After Money Transfer

I get a "ORA-00922 missing or invalid option" after compiling the following trigger:

create or replace
trigger aifer_transfer
after insert on transfer
for each row
[code]......

I want the trigger to affect the transferring account (from_account) with minus the "amount" being transferred from it, and the account transferred to (to_account) with plus the "amount" being transferred to it. My tables looks as following:

TRANSFER
----------------------------------------- -------- ------------
ROWNR NOT NULL NUMBER(9)
PNO NOT NULL VARCHAR2(11)
FROM_ACCOUNTNO NOT NULL NUMBER(8)
TO_ACCOUNTNO NOT NULL NUMBER(8)
AMOUNT NUMBER(10,2)
DATE NOT NULL DATE

ACCOUNT Null? Type
----------------------------------------- -------- ------------
ACCOUNTNO NOT NULL NUMBER(8)
KTNR NOT NULL NUMBER(6)
REGDATE NOT NULL DATE
BALANCE NUMBER(10,2)