cx_obl_model_error Exception in cl_binary_relation=>read_links_of_objects

[1MoreDev]

Hi, i need to get the Notes atached to a Purchase Order in my print program that is called from COR2.

But im having a problem: cl_binary_relation=>read_links_of_objects is returning the exception cx_obl_model_error.

The strange thing here is that, with the same Purchase Order if i use this method on SE24 i get the same exception, but only at the first run, if i run the method again with the same data it returns the links.

What could be the problem ?

  ls_objects-instid = p_order_num. "Purchase order number
  ls_objects-typeid = 'BUS0001'.
  ls_objects-catid = 'BO'.

  "Append the object to the object table "
  APPEND ls_objects TO lt_objects.

  "Get the links for atachments"
  try.
      cl_binary_relation=>read_links_of_objects(
        EXPORTING
          it_objects = lt_objects
        IMPORTING
          et_links_a = lt_links_a ).

    CATCH cx_obl_model_error.
    CATCH cx_obl_parameter_error.
    CATCH cx_obl_internal_error.
  ENDTRY.

Any possibilites are welcome

Regards.

[1MoreDev]

Just in case, i tried to populate even fields that i though not obligatory and it solved my problem somehow.

Anyway if someone has some idea about why i have to populate them it is apreciated.

Now i pass the Relation type 'NOTE' and role 'GOSAPPLOBJ' and it fixed the problem.

  " Build object with document number type and category"
  ls_objects-instid = p_order_num.
  ls_objects-typeid = 'BUS0001'
  ls_objects-catid = 'BO'.
  "Append the object to the object table "
  APPEND ls_objects TO lt_objects.

  "Build the relation type table to get only notes
  wa_rel_opt-sign   = 'I'.
  wa_rel_opt-option = 'EQ'.
  wa_rel_opt-low    = 'NOTE'.
  "Append the relation type
  APPEND wa_rel_opt TO it_rel_opt.

  "Build role table for GOS
  wa_rol-sign   = 'I'.
  wa_rol-option = 'EQ'.
  wa_rol-low    = 'GOSAPPLOBJ'.

  "Append the role type
  APPEND wa_rol TO it_rol.

  "Get the links for atachments"
  TRY.
      cl_binary_relation=>read_links_of_objects(
        EXPORTING
          it_objects          = lt_objects
          it_role_options     = it_rol
          it_relation_options = it_rel_opt
        IMPORTING
          et_links_a = lt_links_a ).

    CATCH cx_obl_model_error.
    CATCH cx_obl_parameter_error.
    CATCH cx_obl_internal_error.
  ENDTRY.

Regards.