DropdownListBox ->onClientSelect ->onInputProcessing

Hello Forum!

I have two dropdownlistbox in my page. Well, When i select a item in the first one i need to go to the onInputProcessing event to load a table or fill with the selection of the first one..to load a table in the second one..

I know more or less how to do it but it appears some errors when i select an item on the first one..

This is the code:

<htmlb:gridLayoutCell  columnIndex         = "2"
                              rowIndex                     = "1"
                              verticalAlignment            = "middle"
                              horizontalAlignment          = "left" >

                 <htmlb:dropdownListBox  id                = "agent"
                                         nameOfKeyColumn   = "KEY"
                                         nameOfValueColumn = "VALUE"
                                         selection         = "<%= agent_1 %>"
                                         onClientSelect    = "oninputprocessing()" >

And on the onInputProcessing event:

IF event_id = cl_htmlb_manager=>event_id.

DATA: event  TYPE REF TO cl_htmlb_event,
      drop_event TYPE REF TO CL_HTMLB_EVENT_SELECTION.


 event ?= cl_htmlb_manager=>get_event( runtime->server->request ).


 IF event->name = 'dropdownListBox ' AND event->event_type = 'clientselect'.
  button_event ?= event.

  CASE drop_event->id.

     WHEN 'agent'.
.
.
.
* Here i fill a table with the attribute page <b><i>agent_1</i></b>
.
.

Maybe it would be easy with javascript.. but is this correct¿?

Thanks in advanced!

Mon