@Reiner30, @jumbo
I see only now that I did put my reaction in dutch. Sorry!
I followed the suggestions of Reiner and they seem to work. I can see now a sitemap and redelivered it to Google via Google Webmaster. Now I have to wait a few days.
If no result, Jumbo, I will act as you have suggested.
Thanks for your help.
Kind regards,
Rudolph Smits