How can I make the item required when line type is goods on purchase order lines with VBS

Summary: We are willing to make the Item a required field when the Line Type is Goods when creating a new line in a redwood purchase order.

Content (please ensure you mask any confidential information):

We are migrating all our Procurement screens to Redwood. Customizations can be made via VBS.

I have selected the 'Purchase Order - Edit' screen in VBS.
I have added the following rule:

And in the Lines Table region I have set the field 'ItemVF' to Required.

Testing the VBS setting does not give any result.
Am I using the correct fields in the correct regions and is the condition correct?