I have created AET fields and added in service order search and result.user want to sort these fields in scending order and descending order.but the functionality is not working in our service order search result?

Hi Experts,

I am facing the problem ,I have created  AET fields and added in service order search and result.user want to sort these fields in Descending order and descending order.but the functionality is not working in our service order search result?

I have added the logic as below in do_prepare_output method..this is not working could you please tell me the process how to do it.

METHOD do_prepare_output.

  gv_sort_direction = 'D'.

  gv_sort_column = '/customer date'.

  sort( ).

ENDMETHOD.