It's my experience that if you do not have a markup table, you must have a Rate table for all items. We don;t mark up our subs and materials, so I keep the Markup blank and then created "Pass-through" rates for my Mat, Subs, etc.

When setting up the Type and Table ID for the Rate Table Add Category for Available key columns and "Pass-Through Cost" at the Available field column section, and then check the box on the corresponding table.