How to report your problem productively in the Unity3D forums:
This is the bare minimum of information to report:
- what you want
- what you tried
- what you expected to happen
- what actually happened, especially any errors you see
- links to documentation you used to cross-check your work (CRITICAL!!!)
If you post a code snippet, ALWAYS USE CODE TAGS:
How to use code tags: https://discussions.unity.com/t/481379
Just a guess: make sure you apply all transforms (scale and rotation) before exporting.