How to Solve Auto Insert Date-Time Problem with SQLLOADER?

Dear Experts,

I have a table like below:

CREATE TABLE TA
   (      X DATE,
      Y VARCHAR2(255 BYTE),
      Z VARCHAR2(31 BYTE),
      T VARCHAR2(127 BYTE),
      K VARCHAR2(127 BYTE),
      L VARCHAR2(127 BYTE),
      M CLOB,
      N DATE DEFAULT SYSDATE
   )

N is going to be filled for each record while insertion. (There is no corresponding N field in the input file.)

Control File is like this:

LOAD DATA  ....
INFILE   ....
BADFILE  ....
DISCARDFILE ....
APPEND INTO TABLE TA
Fields terminated by "|"
TRAILING NULLCOLS
(
X DATE "MON DD HH24:MI:SS" NULLIF (X="NULL"),Y,Z,T,K,L,M,N DATE "MON DD HH24:MI:SS" NULLIF (INSERT_DATETIME="NULL")
)

Each record is being properly recorded to Table, however the field N (field for auto-insert date-time) comes always NULL. What can it be?

BR