Plotting Custom Fields in HFSS

Hi, so I've gotten quite used to plotting regular E fields and the like. My goal this time was to plot the y-projection of the E field. I went to the field calculator, dotted the E field with the y unit vector, and saved the result. I've also selected a geometry, which I assume means in this case the surface I want to plot on. Still, my field and this geometry cannot be evaluated (I'd think this is the right function). What am I doing wrong?