Frm-10902 invalid sql query

hi i have the following sql running in toad IDE
  select obj_child, child_id, obj_id, obj_name, obj_parent, parent_id
from
(
select oc.obj_name obj_child,
       ec.obj_child child_id,
       c.cal_objid obj_id, c.obj_name, c.obj_type, c.obj_title, c.description,
       op.obj_name obj_parent,
       ep.obj_parent parent_id
  from object_list c,  
  cal_erd ec,
  object_list oc,
  cal_erd ep ,
  object_list op
  where ec.obj_parent(+) = c.cal_objid  -- if object is no parent still get an empty row
  and   ec.obj_child  = oc.cal_objid(+) -- if no child relation found stil get an empty row to get empty child-data
  and   ep.obj_child(+)  = c.cal_objid  -- if object is not a child still get an empty row
  and   ep.obj_parent = op.cal_objid(+) -- if no parent relation found stil get an empty row to get empty parent-data
)

BUT when i put same sql in to create record group am geting this error

am in oracle form 11gR2