SQL & PL/SQL

The output in a column is getting truncated when i use CLOB instead of varchar2. Can someone tell me why?

Code:

CREATE OR REPLACE FUNCTION get_accounts (p_LOGIN  in  Siebel.s_Contact.LOGIN%TYPE)

  RETURN VARCHAR2

IS

  l_text VARCHAR2(32767) := NULL;

BEGIN

  FOR cur_rec IN (SELECT Account.OU_NUM FROM siebel.s_org_ext Account, siebel.s_contact Contact, siebel.s_party_per Inter

  WHERE p_LOGIN = Contact.Login and Contact.row_id = Inter.person_id and Inter.party_id = Account.row_id and Account.accnt_type_cd ='Billing') LOOP

    l_text := l_text || ',' || cur_rec.OU_NUM;

  END LOOP;

  RETURN LTRIM(l_text, ',');

END;

/

SHOW ERRORS

SET PAGESIZE 50000

SET MARKUP HTML ON SPOOL ON

SET LINESIZE  95

SET ECHO off

SET FEEDBACK OFF

SET TERMOUT OFF

spool  $OUTFILE1

WHENEVER SQLERROR EXIT SQL.SQLCODE

COLUMN Username FORMAT A25

COLUMN "Common Name" FORMAT A150

COLUMN Email   FORMAT A50

Column "Last login timestamp"    FORMAT A20

SELECT A.login "Username", B.fst_name ||' '||B.last_name "Common Name", B.email_addr "Email", A.last_login_ts "Last login timestamp",

       B.x_selected_accnt_id "Last visited account", get_accounts(A.login) as "Account List"

from siebel.s_user A , siebel.s_contact B

where A.last_login_ts > SYSDATE-7 and A.par_row_id = B.PAR_ROW_ID

      order by A.last_login_ts asc;

OUTPUT:

The last column values are truncated.

Any help is appreciated. Thanks