Issue in datapackage size in DTP

Dear All,

I have created an end routine where I require to populate EXC_DOC_NUM by doing look-up at ZFIAR001 using 0ALLOC_NMBR and 0DOC_DATE.

The problem here is that when I keep data packet size = 50,000 then EXC_DOC_NUM does not get populated. But when I use data packet size = 500, the field  EXC_DOC_NUM gets populated.

Can you tell me the reason why this is happening?

Below is the code written by me:

FIELD-SYMBOLS:  LIKE LINE OF RESULT_PACKAGE.

  SELECT

      AC_DOC_NO

      DOC_DATE

     /BIC/ZEXCIDOC

      DEB_CRE_LC

      DEB_CRE_DC

•    INTO CORRESPONDING FIELDS OF TABLE I_AR_LINE_ITEMS

         FROM /BIC/AZFIAR00100

          INTO TABLE I_AR_LINE_ITEMS

         FOR ALL ENTRIES IN RESULT_PACKAGE

         WHERE

        /BIC/ZEXCIDOC = RESULT_PACKAGE-ALLOC_NMBR

        AND

        DOC_DATE = RESULT_PACKAGE-DOC_DATE.

IF SY-SUBRC = 0.

  SORT I_AR_LINE_ITEMS BY DOC_NO DOC_DATE EXC_DOC_NUM.

  ENDIF.

  LOOP AT RESULT_PACKAGE ASSIGNING -/bic/zamountlc = WA_AR_LINE_ITEMS-DEB_CRE_LC

        .

      ENDIF.

  ENDLOOP.

Thanks in advance,

Ravi Rawat