Hi,
You try like this way
*-------------------------------------------
Convert the OTF data to binary PDF
CALL FUNCTION 'CONVERT_OTF_2_PDF'
IMPORTING
bin_filesize = lv_bin_filesize
TABLES
otf = lwa_document_info-otfdata
doctab_archive = lit_docs
lines = lit_docline
EXCEPTIONS
err_conv_not_possible = 1
err_otf_mc_noendmarker = 2
OTHERS = 3.
IF sy-subrc <> 0.
MESSAGE e025(zftm) .
ENDIF.
REFRESH lit_content_txt.
LOOP AT lwa_document_info-otfdata INTO lwa_otf.
CLEAR lwa_content.
CONCATENATE lwa_otf-tdprintcom lwa_otf-tdprintpar
INTO lwa_content.
APPEND lwa_content TO lit_content_txt.
ENDLOOP.
REFRESH : lit_content_hex,
lit_objhead.
CLEAR : lv_transfer_bin,
lv_len.
* FM to convert OTF to PDF
CALL FUNCTION 'SX_OBJECT_CONVERT_OTF_PDF'
EXPORTING
format_src = 'OTF'
format_dst = 'PDF'
CHANGING
transfer_bin = lv_transfer_bin
content_txt = lit_content_txt
content_bin = lit_content_hex
objhead = lit_objhead
len = lv_len
EXCEPTIONS
err_conv_failed = 1
OTHERS = 2.
IF sy-subrc <> 0.
MESSAGE ID sy-msgid TYPE sy-msgty NUMBER sy-msgno
WITH sy-msgv1 sy-msgv2 sy-msgv3 sy-msgv4.
ENDIF.
CALL FUNCTION 'SAP_WAPI_ATTACHMENT_ADD'
EXPORTING
WORKITEM_ID = '21402'
ATT_HEADER = LV_SWR_ATT_HEADER
ATT_BIN = lit_content_hex
* DOCUMENT_OWNER = me->wa_request-CREATEDBY
LANGUAGE = SY-LANGU
DO_COMMIT = 'X'
IMPORTING
* RETURN_CODE =
ATT_ID = LV_ATTACHMENT
* TABLES
* MESSAGE_LINES =
* MESSAGE_STRUCT =
.
*----------------------------------------------