mode analysis, not getting the right neff

Hi:
I am solving one file using Comsol 3.5a but I am getting neff to be 3.8. I am supposed to get it 3.88.
Can anyone check why my neff does not go higher?. I have been trying for days and the best thing I could reach is 3.82 . I really need to get 3.88 as it is the mode I am searching for. The file is attached.
Naema