Error messages in MVC

Hi,

In the do_handle_event of one of my subcontollers I insert an error message if a condition was not met.

...

...

ELSE.

me->messages->add_message(

condition = 'wa_numreturn'

message = 'The number entered does not exist.'

severity = me->messages->CO_SEVERITY_ERROR ).

ENDIF.

I have included the following code to display the error in the view called by the above subcontroller:

<htmlb:textView text = "<%= page->messages->assert_message( 'wa_numreturn' )%>"

textColor = "red"

wrapping = "FALSE" />

However, the message is not displayed even though the code in the do_handle_event gets executed.

Can the "condition" for messages be any text or should it be a attribute in the controller & view?

Could someone please let me know why the message is not passed from the controller to the view? Do I need to pass it explicitly?

Thanks.