Creation of settlement documents, how to influence

Question

Hi  team ABAP,
i have a requirement to influence creation of settlement documents which get created via TA MEB1 using the pushbutton "Settlement".
There is a SMOD/CMOD project which we use as userexit.
we use SMOD lwbon003, component EXIT_SAPLWN01_003.
i dont need to do much, i just need to "enrich" those settlements with LIFNR, PRCTR and MWSKZ.
the local interface of my exit component EXIT_SAPLWN01_003 looks like following:
*"*"Lokale Schnittstelle:
*"  IMPORTING
*"     VALUE(I_ARRANGEMENT) LIKE  KONA STRUCTURE  KONA
*"     VALUE(I_SETTLEMENT_VALUES) LIKE  ARRANG_VAL STRUCTURE  ARRANG_VAL
*"     VALUE(I_VARIABLE_KEY) LIKE  VAKE STRUCTURE  VAKE
*"     VALUE(I_CONDITION_RECORD) LIKE  KONP STRUCTURE  KONP
*"     VALUE(I_CONDITION_SCALE) LIKE  CONDSCALE STRUCTURE  CONDSCALE
*"     VALUE(I_T6B1) LIKE  T6B1 STRUCTURE  T6B1
*"  EXPORTING
*"     REFERENCE(E_SETTLEMENT_VALUES) LIKE  ARRANG_VAL STRUCTURE
*"        ARRANG_VAL
*"  TABLES
*"      T_VARIABLE_KEY STRUCTURE  VAKE
*"      T_CONDITION_RECORD STRUCTURE  KONP
*"      T_CONDITION_SCALE STRUCTURE  CONDSCALE
*"      T_SETTLEMENT_VALUES_MWSKZ STRUCTURE  ARRANGVALW
*"      T_SETTLEMENT_VALUES_WERKS STRUCTURE  ARRANGVALW
*"      T_ERROR_MESSAGES STRUCTURE  ARRANG_ERR
*"  EXCEPTIONS
*"      ERROR_MSG_SETTLEMENT_VALID
*"      ERROR_MSG_SETTLEMENT_INVALID
*"      FATAL_ERROR_MSG_USER_EXIT
I´ve tried a lot, but nothing really worked out, does anyone have expierience in how to use this interface correctly?
Well LIFNR works fine... but the rest.
I have tried to change MWSKZ in the one existing record i got in parameter T_SETTLEMENT_VALUES_MWSKZ .
It was displayed in the simulate screen, but no tax was calculated and posted, in the FI document the old MWSKZ showed up which was in my record BEFORE i changed it.
Next thing i tired is to add a second record into parameter T_SETTLEMENT_VALUES_MWSKZ, used some imaginary 10% tax calculated the value myself and added the record. Didnt work out either.
Im kinda stuck here, maybe someone can give me a tip.
thx for sharing your time.

Answer 1

Ok, Problem finally solved.
After reading the ducomentation on the EXIT a bit i could correct some problems with filling the structures properly which enabled me make him calculate tax as i want.
For the assignment of the FI-documents to the profit center we used a FI-substitution.