I choose a hero to play a skirmish with and make a selection under all the options in the skirmish menu (including the rules and so on), but the gauntlet with the upward pointing thumb that I would presumably have to click on to start the skirmish remains greyed out and I can't work out why.

I am playing the most recent gog release of this game. Can anybody help with this?

Thank you. It never occurred to me that I needed to actively add myself to the match. Problem solved.