Hello Sreekanth,
When you are creating contracts using BAPI_CONTRACT_CREATEFROMDATA, you must had 3 function partenrs to create the contract.
Try:
DO 3 TIMES.
CASE syst-index.
WHEN 1. wa_contract_partners-partn_role = 'PH'.
WHEN 2. wa_contract_partners-partn_role = 'WE'.
WHEN 3. wa_contract_partners-partn_role = 'AG'.
ENDCASE.
wa_contract_partners-partn_numb = ls_header_data-value_0006.
APPEND wa_contract_partners TO bapi-contract_partners.
FREE wa_contract_partners.
ENDDO.