String variable doesn't work

Hello community,

I’m following the Using Variables tutorial (, started at 25min.) now. Everything works fine except for creating string variables. When I selected the currentitem, it supposed to change the image from image 1 to image 2. However, when I selected the currentitem under assign variable, the currentitem shows a cross line and the image remained the same. Didn’t go to image 2. I restarted this section and followed the tutorial to test it again, it showed the same error. Does anyone know how to fixt it?

This is my Figma test: