Can't export model from Blender to Babylon.js

Hi, 

I use new version of Blender(2.78a) and I have my model in it, so I tried to export it to .babylon file.
I got exporter file from Github just now and I have already move io_export_babylon.py to Blender's addons.
When I tried to export my model it got this error(in the picture that I have attached), but when I tried to export a normal cube, I could do it.
With the same model, I can do it with the babylon exporter that come with babylon v2.4 and previous version of Blender.
But for both new version of Blender and Babylon i can't.

Thank you in advance
Peace