Maintenance activity type - PM order

Question

Hello,
I have to configure the field "activity type" on PM order (tcode IW31).
I want to make this field obrigatory and It can't come with default values. It must comes empty.
In SPRO, when a take off the link between the Order type and the default value for activity type (table T350), occurs the error bellow, on tcode IW31:
"No maintenance activity type could be determined"
After that, occurs a runtime error, and I can't enter in the IW31 to create the PM order.
Somebody knows how can I do what I need?
Tks, Camila.

Answer 1

Message 2 (second part):
Source Code Extract                                                                               
Line  SourceCde                                                                               
1 FUNCTION t350_read.                                                     
    2 *"----
    3 ""Lokale Schnittstelle:                                               
    4 *"  IMPORTING                                                           
    5 *"     VALUE(AUART) LIKE  T350-AUART                                    
    6 *"     VALUE(LANGUAGE) LIKE  SY-LANGU DEFAULT SY-LANGU                  
    7 *"     VALUE(MTYPE) LIKE  SY-MSGTY DEFAULT ' '                          
    8 *"  EXPORTING                                                           
    9 *"     VALUE(ILART_TEXT) LIKE  T353I_T-ILATX                            
   10 *"     VALUE(T350_WA) LIKE  T350 STRUCTURE  T350                        
   11 *"  EXCEPTIONS                                                          
   12 *"      NO_T350_ENTRY                                                   
   13 *"----
   14                                                                         
   15                                                                         
   16 *--- Pufferung übergeben -
   17   t350_wa = t350.                                                       
   18   ilart_text = t353i_t-ilatx.                                           
   19 *--- nur weiter wenn noch nicht gelesen -
   20   CHECK t350-auart <> auart.                                            
   21                                                                         
   22 *--- Lesen Vorschlag ILA zur Auftragsart -
   23   SELECT SINGLE * FROM  t350                                            
   24          WHERE  auart       = auart.                                    
   25                                                                         
   26   IF sy-subrc <> 0.                                                     
   27     if mtype <> space.                                                  
        MESSAGE ID 'I0' TYPE mtype NUMBER '226'                          
   29           RAISING no_t350_entry.                                        
   30     endif.                                                              
   31   ELSE.                                                                 
   32 *--- Übergeben T350 Workarea -
   33     t350_wa = t350.                                                     
   34 *-> nur wenn nicht im Puffer und Sprache spezifiziert                   
   35     IF t353i_t-ilart <> t350-ilart and                                  
   36        not language is initial.                                         
   37 *--- lesen Text zur ILART -
   38       SELECT SINGLE * FROM  t353i_t                                     
   39              WHERE  spras       = language                              
   40              AND    ilart       = t350-ilart.                           
   41 *--- Übergeben Text zur ILART -
   42       ilart_text = t353i_t-ilatx.                                       
   43     ENDIF.                                                              
   44   ENDIF.                                                                
   45                                                                         
   46 ENDFUNCTION.
Edited by: Camila Peralta on Jun 22, 2010 2:17 PM