Unable to set dimensions in Measurements box

I recently downloaded SketchUp Make 2017. While following the instruction video Starting with SketchUp- part 2, I faced a difficulty. I am not able to define dimensions in the box at the lower right corner.
It seems that I cannot put a cursor there / I am not able to change or type dimensions in the box.
Who does know how to manage that? Thank you in advance!

Don’t attempt to click in the box.
Just start your action, let go of the mouse, type what you want and hit enter.
The program is always listening for input.

Thank you.
At first, it didn’t seem to work that way. However, now I managed it.