Why is my rig AI headless

Hi all
I am making a horror game in which a creepy doll is the antagonist.The doll I had before was not that creepy so I downlaoded a free doll head from the creator marketplace which is this one [https://create.roblox.com/marketplace/asset/3147163924/Creepy-Doll-Head?pageNumber=1&pagePosition=0&keyword=+doll+head]
but after I renamed it to ‘Head’ and put it in the Doll and tested the game the doll was headless but its AI was still functional.

I really don’t know the reason behind this and was wondering if anyone here can help me out pleas

Thank you!

Have you checked to make sure all the descendants (children) of the new head match the original? It should be attached to the torso using a Motor6D, if you’re using a default Humanoid-based NPC! (This would be R6 or R15!)