2lis_03_BF enhancement Using BADI

Dear Experts,

I have a requirement of enhancing the datasource of 2LIS_03_BF with an ZZ-Fields.

my code ;

method IF_EX_RSU5_SAPI_BADI~DATA_TRANSFORM.
    check I_DATASOURCE = '2LIS_03_BF'.

    types: begin of T_MKPF,
            MBLNR   type MBLNR,
            MJAHR   type MJAHR,
            ZZSPED  type XLIFNR,
            ZZZLETY type ZZZLETY,
           end of t_mkpf,

           begin of t_mblnr,
              mblnr type mkpf-MBLNR,
           end of t_mblnr.

    data: lt_mblnr type table of t_mblnr,
          lt_mkpf type table of t_mkpf,
          LF_LINES type I.

    field-symbols: <FS_DATA> type MC03BF0.

    select MBLNR
    into table LT_MKPF
    from MKPF for all entries in LT_MBLNR
    where mblnr = LT_MBLNR-mblnr.

    loop at C_T_DATA assigning <FS_DATA>.

      read table LT_MKPF assigning field-symbol(<FS_MKPF>)
      with key MBLNR = <FS_DATA>-MBLNR.
      if SY-SUBCS = 0.
        <FS_DATA>-ZZSPED    = <FS_MKPF>-ZZSPED.
        <FS_DATA>-ZZZLETY   = <FS_MKPF>-ZZZLETY.
      endif.

i got a Bugs. Can any one help me in this regard ?

thx alot for correction,

Regards