Why isn't my Blender model smooth when I import it?

So I have a model that used to be smooth in Blender but then one day when I started up Blender it wasn’t smooth. I unchecked (auto smooth) and then it was smooth again. So I imported it to Unreal and then the model wasn’t smooth. Here’s the comparison:

Recompute Normals and Recompute Tangents are enabled so why is it not smooth? Also whenever I import it is says it has no smoothing groups.

when you export from blender you must change smoothing group from normals to faces. On the newest version of blender, 2.77 it is listed under geometry tab and in older versions just scroll down until you see it.

Worked for me ! Thanks, totally forgot about that option !