Trigger roundtrip for date field

Hi All,

How to make a date field trigger a round trip after user chosed a date?

I did the following in P, but it does not trigger it.

    case iv_property.

  when if_bsp_wd_model_setter_getter=>fp_fieldtype.

    rv_value = cl_bsp_dlc_view_descriptor=>if_bsp_dlc_view_descriptor~field_type_input.

  when if_bsp_wd_model_setter_getter=>fp_server_event .
    rv_value = 'ENTER'.
  endcase.

tks for your hints in advance.