FollowMe tool problem

I am trying to make a cell phone case in Sketchup Make. I start with a 1 mm thick rectangular base,
and then I try to create a half-circle shell , 8 mm. high, around it. Which should be a job for the followme tool. I start with a semicircle, offset it to get a slightly smaller semicircle, then close it up so it becomes a surface. It is attached at the front edge of my base. Then I use the follwme tool to pull it back along one edge of the rectangular base, but it will not actually follow me all the way around the perimeter. It stops at the end of the first edge of the base. Am I doing something wrong?

Thanks in advance for any tips.

Could you attach your model (pre-pushpull) here? There could be either a flaw in the setup or a flaw in your technique, but I can’t tell from your description.

instead of doing a manual ‘Follow Me’ along some connected edges (the rectangle) you should let SU do the job. Select the rectangular face, then select the ‘Follow Me’ tool and click with its cursor tool tip on the profile that needs to follow (the path, the perimeter of the rectangle).

You may need to work at a larger scale, for SketchUp isn’t too happy creating small faces with very short edges as their boundaries.