I'm trying to determine the contact pressure (plot) between two pieces of metal that are bolted together. I've got a linear static run setup with all of my fasteners pre-loaded & a contact interface defined between the two plates.

My run completes successfully & I am able to see the local fastener pre-load stress under the head of the bolts. When I go to define a stress plot -> contact pressure, the plot shows a min/max of zero. Is there something I'm doing wrong here with this setup?