Making a dome

Ive been trying to make a dome but every time i create one it has a hole in the top
Im folowing all the instructions implicitly.
Firstly I create a circle on the ground plane Next I create a semi-circle along the blue plane. Then I select the outer edge of the first circle then select the follow me tool and click on the semi-circle.
A dome is created but with a hole in the top.

I’m using the web version of SketchUp

Any ideas anyone?

Small scale, try 10x or more.


Thanks mihai
That worked.