These are new items, the Flat Boots.
Please detach "Feet" of the body parts to wear the boots.
Try on the DEMO, please!
Thank you so much.
All DOLL COCO items are RIGGED MESH.
You need to use a MESH ENABLED VIEWER to see the MESH items.
(The official SL viewer, later Version 3)
The bones of DOLL are different positions from SL standard avatars.
Your standard avatars can not wear DOLL clothing.
Please remove the body parts overlapping the DOLL clothes,
when you wear them.
DOLL COCO blog
DOLL COCO blog (Japanese)