How to do substitution in FI for complete document using user exit in abap

[former_member616311]

My requirement is that I have to populate the value of lifnr from account type k to another line item's assignment field whose account no will be '24873201' .Whenever this account no will come for a po in miro then the value of lifnr will be populated from account key k line item.

For this I have tried at line item level but it is not working as I have to fetch from another line item and poulate it to another one and after that I have tried at complete document level by using a referece code but it is still not triggering there. I had put a breakpoint also but it is not going there and while checking that substitution in shcb transaction it is showing that my substitution zmiro (which I have used for complete document) not found. I have also generated progarm RGUGBR00.

But I am still getting the message that zmiro not found.

Please refer my above code for correct me..

1. I have made a copy of the program RGGBS000 as ZRGGBS01 .
2. Added the Follwing types in the data section: TYPE-POOLS: GB002.
3. In the FORM GET_EXIT_TITLES TABLES ETAB added the follwoing lines

EXITS-NAME = 'U900'. "Assignment Number substitution
EXITS-PARAM = C_EXIT_PARAM_CLASS.
EXITS-TITLE = TEXT-900. "ZUONR
APPEND EXITS.
FORM u900 USING bool_data TYPE gb002_015. .
  DATA: w_bseg TYPE bseg.
  DATA: w_zuonr TYPE bseg-zuonr.
  READ TABLE bool_data-bseg INTO w_bseg WITH
  KEY koart = 'K'.

  IF NOT bseg-lifnr IS INITIAL.
 sy-subrc = 0.
    w_zuonr = bseg-lifnr.
  ENDIF.
  LOOP AT bool_data-bseg INTO bseg
  WHERE hkont = '24872301'.

    IF bseg-hkont = '24872301'.
      bseg-zuonr = w_zuonr.
    ENDIF.
    MODIFY bool_data-bseg FROM bseg.
  ENDLOOP.

ENDFORM.

[RaymondGiuseppi]

Could you post your initial OBB8 screen and the corresponding substitution in next screen for Call Point 3?