Hi Helga,
when did you add the wait step? Some time after you already sent out the first e-mail, or was it there before?
If you`ve added it some time after your initial send, the contacts have already "left" the campaign, and the "3" you see in the green circle on your e-mail merely indicates that there are 3 people who have not received the e-mail (reasons include bouncebacks, unsubscribes, master exclude).