ME53n fixed vendor is getting deleted.

Question

in IW32 we can create the line item for the Purchase requistion when the controlling key is changed to PM03. like wise when the new line item is getting created thru IW32 the previous line item 's vendor no is getting deleted.
in source of supply tab the screen field is getting deleted MEREQ3322-FLIEF only we add the 2nd line item the previous line item is getting deleted. its not happeni

Answer 1

Hi Srivatsan,
1) create a new SC and set on hold.
2) set a breakpoint in the function B45A_SOURCEDETERMIN_GETSOS at the point:
CALL FUNCTION 'BAPI_SOURCEDETERMIN_GETSOS'       <----- here
            DESTINATION destination
3) execute the FM BBP_PD_SC_TRANSFER with the GUID of the SC (from the step 1)
If you have a dialog user in the bakcend, you can debug the SOS find in the backend. If you just need the result, doubleclick on the sources_of_supply:   
CALL FUNCTION 'BAPI_SOURCEDETERMIN_GETSOS'
      DESTINATION destination
      EXPORTING
        material              = material
        mat_grp               = mat_grp
        plant                 = plant
        deliv_date            = deliv_date
        quantity              = quantity
        unit                  = unit
        item_cat              = item_cat
        acctasscat            = acctasscat
        purch_org             = purch_org
        fixed_vend            = fixed_vend
        pckg_no               = pckg_no
        unit_iso              = unit_iso
      TABLES
        sources_of_supply     = sources_of_supply    <--- check the result here
        return                = return
      EXCEPTIONS
        communication_failure = 1  MESSAGE msg_text
        system_failure        = 2  MESSAGE msg_text
        OTHERS                = 3.
Kind regards,
Peter