Thread Graft on Olive

Is anyone familiar with thread grafting on Olea europaea? I have a very healthy unnamed dwarf specimen that grows well. However, it has some gaps and I put two thread grafts on it in June. They are alive, but not growing. They just sit there. I am spraying them daily with dilute fertilizer. The tree was outdoors all summer and is now under fluorescent lights. Any suggestions or is this species just very slow to graft?
Iris