Make sure the oil is 100% olive oil. If it is a blend of other oils it will throw off your lye calculation because you will not know the percentage of each oil in the blend. Castille is 100% olive oil.
WSP sells a product they call Olive Oil-Pomace which is a blend of pomace and vegetable oils. This tripped me up some time ago. So I should have been more clear in pointing out to just make sure the pomace is 100% olive oil. Sometimes the name may be deceiving.