MESSAGE WHEN I TRY TO CHANGE THE ITEM MODEL GROUP FROM STANDARD COST TO WEIGHTED AVERAGE

Hi: When I try to change one item´s Item model group from Standard cost o Weighted average I have this message:

The item is set to be evaluated by inventory model 'Standard cost'. The system cannot convert the item to be evaluated by an inventory model of type 'Transactions settled' only inventory models of type 'Transactions not settled' can be selected

For more information, the item have 0 cost an 0 quantity at this moment

I appreciate any help with this issue

Thanks in advance,