How to add a double bar

[Melisande]

I want to add a double bar to the left of a certain measure. I select the measure icon, then double click on the measure. The measure dialogue box comes up. I select double bar on the left and click OK. The measure dialogue box goes away, but nothing happens. No double bar is inserted. What is up with that? How do I insert a double bar?

[motet]

The "left barline" setting only works on the first measure of a system. Instead, set the right barline of the previous measure.