Sobek's archway

I have tried all the hints including uhs and all have failed. Does anyone have any ideas because I am unable to get anywhere. The door just will not open!

book of ends says click on arch stones 12/18/20/9/3/7 strictly in that order, counting
from stone 1 which is at the bottom left of the arch. When door rotates click on back
of it when the back is facing you and it takes you to crocodile cove