Hi Haung,
You need to use FREE_HELP not the component name.
Modify you code as below:
LT_RANGE_TABLE_V = wd_this->m_handler_V->create_range_table( 'ZCYPHDATE' ).
wd_this->M_HANDLER_V->add_selection_field(
i_id = 'ZCYPHDATE'
it_result = LT_RANGE_TABLE_V
i_value_help_type = if_wd_value_help_handler=>CO_PREFIX_APPLDEV
i_value_help_id = 'FREE_HELP'
i_no_intervals = abap_false ).
Hope this helps you.
Regards,
Rama