Allowing partial cases to be sold?

I want to be able to sell partial cases of an item.

I get this error when I try saving an sales order with a partial item:
Row 8: Quantity (0.35) cannot be a fraction. To allow this, disable ’ Must be Whole Number ’ in UOM Each .

I then looked under UOM setting, and I saw no setting saying: Must be Whole Number

Thanks for any ideas on how to fix this.