Update unloading point and means of transport type using sd sales document change function module

Hi Team,

I want to modify unloading point and means of transport type using SD_SALES_DOCUMENT_CHANGE function module,but it's not happening even if i provide the values as follow in PARTNERS and PARTNERCHANGES table.

    t_partner-partn_role = c_lf.                       "LF vendor

    t_partner-partn_numb = wa_sales-parvw.  "Partner number

    t_partner-unload_pt = wa_sales-ablad.      "Unloading Point  

    APPEND t_partner.

    t_part_change-document = wa_sales-vbeln.

    t_part_change-partn_role = c_lf.

     t_part_change-p_numb_new = wa_sales-parvw.

    t_part_change-updateflag = c_upd.

    APPEND t_part_change.

Please provide your valuable input in resolve this issue.

Thanks,

Ajay