Clothing tool error

I’m trying to create flag, and I follow the video Blender UE4 Cloth - YouTube

but 3 error messages appear.

–This APEX clothing asset doesn’t have Tangents data! It could be old format. This can introduce rendering artifact.

–There are no corresponding bones. At least one bone should exist. This Could be Improper APEX file.Mapping failed bones :

–An error occurred using this clothing asset for this skeletal mesh material section.

Please help!!!

looks fine in Apex editor, but when I import to ue4, once apply apx file to material things goes wrong and up side down the texture.