Loop cut is not working for me

i just started using Blender. I have an object, put my cursor over the edge, hit ctrl+r and nothing happens. I also tried CMD+r cause i’m on a mac. Where’s all my happiness?

For testing purposes just use the standard cube. Select edit mode and select all by pressing “a”". Then press CRTL-r and move the cursor above any edge of the cube an you will get a violet indication where the edges will be cut. Accept with the LMB. Now you can slide the cuts along the cut edges. Accept with the LMB again and the cut will be applied to the cube.

This is working on a Mac as well.

thank you. Edit mode. I’m an idiot. I really appreciate it.