PO(Purchase Order) Submitted - follow the naming provided as on exam you need to copy paste some of the formulas.They will not be recognized if your line items have different names, should be 'PO Submitted'
Confirmed PO Delivery, think about second part of your formula, whether you should be looking at Shipping Time Weeks or other, similar line items
You should also review your Confirm Purchase Order Receipt line item formula, the part within POST function
Ending Inventory, review line item, you have your starting inventory, then some forecast demand, but confirm PO receipt should not be substracted
Safety stock target you should use different formula than WEEKVALUE
Good luck! Let me know if you have some questions.