Punchout - Invalid Field Value 000

What do I do if I receive the following error message:
You have entered an Invalid Field Value 000 for the following field: item

This error comes up when the NetSuite master item being saved on the transaction line is not valid in one way or another. This generally happens when (a) the item is not enabled for the subsidiary that the transaction is being saved in or (b) the item is missing a value in the expense account field.