Tax Error on PO with Location without Country -- Determine Place of Supply: Shipto, use Bilto if shi

 We have set up Tax in a new operating unit. The PO users are sometimes using Dummy Locations without a country.And in this case the Tax Errors out. 

I tried to create a rule to make the PO Tax Not Applicable when the Shipto country is NULL, however that is not possible with the Tax Determination Sets and Condition Sets.

However, as my Determine Place of Supply Rule is set to:   Ship to, Use Bill to if Shipto is not found., the PO should in my opinion not give an error if there is no Shipto Country.

It should simply look at the Bill to.