iby_disbursement_setup_pub.Set_Payee_Instr_Assignment returns error as INVALID_PARTY_CONTEXT

Hi,

Could you pl help identify the issue related to API: iby_disbursement_setup_pub.Set_Payee_Instr_Assignment returns error as (P1=INVALID_PARTY_CONTEXT) (P2=) (P3=).

API Input values  -

    r_payee_instr.payment_function := 'PAYABLES_DISB';
    r_payee_instr.party_id := p_payee_party_id;
    r_payee_instr.org_type := 'OPERATING_UNIT';
    r_payee_instr.org_id := p_org_id;
    r_payee_instr.party_site_id := p_payee_party_site_id;
    r_payee_instr.supplier_site_id := p_supplier_site_id;

    r_assignment_attribs.Instrument.Instrument_Type := 'BANKACCOUNT' ;
    r_assignment_attribs.Instrument.Instrument_Id := p_ext_bank_acct_id ;