Custom Task View for Due Date is Empty

Custom Task View for Due Date is Empty

I want to create a custom view so I can easily call up tasks for which due dates have not been assigned, so that I can go through and assign due dates to them.

Is this possible? I tried to create such a view by selecting "due date" "is" and then leaving the criteria blank. However Projects will not let me save such a view and instead insists I make a selection for criteria such as "this month" etc.

Thank You