Determination in Delegated Node.

Hi Experts,

I am trying to determine the STUDENTID in the delegated Node. Determination is working fine but after determination it is Setting All Host Keys i.e. HOST_BO_KEY, HOST_KEY, HOST_NODE_KEY to '00000000000000000000000000000000'. The below is my code.

DATA  :   ls_key          TYPE          /bobf/s_frw_key,

               ls_modify       TYPE          /bobf/s_frw_modification,

               lt_modify       TYPE          /bobf/t_frw_modification,

               lr_ref_data     TYPE REF TO   zst_s_student1.

  READ TABLE it_key INTO ls_key INDEX 1.

  CHECK ls_key IS NOT INITIAL.

  CREATE DATA lr_ref_data.

*Getting lr_ref_data->studid  from SNRO.

     ls_modify-key = ls_key-key.

     ls_modify-change_mode = /bobf/if_frw_c=>sc_modify_update.

     ls_modify-data = lr_ref_data.

     ls_modify-node = zif_st_zstudent_c=>sc_node-student.

     APPEND zif_st_zstudent_c=>sc_node_attribute-student-studid  TO  ls_modify-changed_fields.

     APPEND ls_modify TO lt_modify.

    io_modify->do_modify( it_modification = lt_modify ).

Thanx in Advance,

Pankaj