How to test a 2020 Nissan Sentra rear window defrost grid? (Upper lines)

I got my rear window tinted and I wanted to confirm that my defrost lines work. I found the power and ground connections om the passenger side C pillar. I unhooked the ground wire from the system that was bolted to the body behind the C pillar and attached my test light. I turned on the defrost system and got a light on the button thinner lines to light up. Here's what I don't understand. I got the bottom 2/3s of lines to test good, but when I went to the upper thicker lines I couldn't get a light. The ground for the grid did not appear to attach/connection to the upper thicker lines by following the grid. I looked behind the C pillar panel on the driver's side and did not find a ground there either. are the top dummy lines? I wouldn't think that makes sense, but that's all I could think.

any thoughts?

Thank you!