Question about DISTINCT

I have a script that stores 3 values, email, firstname and lastname in a cursor. The only problem is that it often returns many of the same values due to multiple entries in the database tables I am searching. I tried distinct, but every time the script runs I get an "ORA-01847: day of month must be between 1 and last day of month GHID". When I take out distinct the program runs fine.

Here is my code:

NOW:=SYSDATE;
BEFORE:=NOW - 7;
OPEN output_cur FOR
SELECT
DISTINCT(ME.e_mail),
su.pat_firstname,
su.pat_lastname
FROM
ops_arw.member_pin ME,
ops_arw.subscriber SU,
ops_arw.int_med_claim_summary INT
WHERE
ME.SRV_EMAIL_PREFERENCE ='Y' AND
ME.CERT_NO =SU.CERT_NO AND
ME.CERT_NO =INT.CERT_NO AND
TO_CHAR(TO_DATE(SU.MEM_DOB, 'YYYYMMDD'), 'YYYYMM')=TO_CHAR(ME.MEM_DOB, 'YYYYMM') AND
INT.INSERT_DATE >= BEFORE;


Thanks for the help.

replace


with