Space after Paragraph - Xara Page & Layout Designer 11

I am using the Xara Page & Layout Designer 11, and now, when i try to adjust the paragraph spacing, it doesn't work. I click on the "ab" - button, and then, when I try to write a number to change the paragraph spacing , it dissappears, so it's impossible to change this. It has worked fine until now. Does anyone know what has happened?

Henning

When you say it has worked fine until now, is this in a particular document that it's stopped working? (if for example you try this in a new document does it work?)

Thanks
Rob