Hi
The most of my model are made in Blender 2.72, some in 2.73 and i also tried it with the newest Version 2.76b.
I am pretty sure that it also works with 2.75!
Did you check that the normals are ok in blender?
Be sure that Backface Culling i on in Blender so you can see when the normals are wrong...
What are your export settings?
Has your model animations?
If you like upload your blend file
so i can check the file...