So the answer is on your post, the number of images selected doesn't fit with the number of images of the xml file So you can't click on Finish… This is the case when at least one image is missing. Did you remove images from your source folder prior to use the Import wizard in Autopano?
Yes, when I fisrt select the wrong number of images, then the button is disabeled. That's clear because the number of images dosn't macht to the number in the xml-file, but when I select the right number of images and I can see the correct preview. The button is still disabeled. In this case I have to start all over.