In SW Premium 2014 SP5.0 I seem completely unable to set up a circular symmetry constraint for a static simulation.  Below is an illustration of my sticking point with a very simple "pie section."  It won't let me select an axis for the constraint:

I tried to verify that my "pie slice" was a "Valid Section" for circular symmetry by using a circular pattern feature to re-create the entire disk:

This worked fine with what is apparently the same axis.  Any suggestions what I'm doing wrong? -- John Willett