Forms 10g disable button on tabular form

Hi all,

i'm trying to disable button dynamically on tabular form.

i write this code on post query and when new record instance on block trigger .

  IF  :xxrm_employee_ekstre.INV_KOD ='INTERFACE'

     THEN      

                    Set_Custom_Property('XXRM_EMPLOYEE_EKSTRE.FATURA_OLUSTUR',:SYSTEM.TRIGGER_RECORD, 'ENABLED', TRUE);                                                              

     ELSE

                    Set_Custom_Property('XXRM_EMPLOYEE_EKSTRE.FATURA_OLUSTUR',:SYSTEM.TRIGGER_RECORD, 'ENABLED', FALSE);                       

  END IF;

Here it is the first screen.

But when i scroll down ,buttons property is not changing .like below image:

Is anyone have an idea?