Netatmo - can't get the step 3 done

I try since hours to get the Netatmo binding or better said the pre-setup done, but I fail in step 3 and can’t get it working.
I have set up a new application on the Netatmo page and can see there my client id and the client secret.
When I create the curl line I get back “{“error”:“invalid_request”}” - but I really have no idea why
This is how my curl line looks like (changed the values for secret, user, etc.)
curl -d ‘grant_type=password&client_id=58…720&client_secret=V…stuff…gw&’ ‘

I tried to limit the scope to only read_station but this did not help as well.
What do I do wrong? Did anyone see similar issues and has a hint for me?
(I did try to make use of Netatmo’s php example but seem to run into a different issue there. (not beeing able to call out to netatmo from my webserver))

Thanks for helping,

(I was planing to use the Netatmo binding in openHab 1.8 but did not yet get so far to touch this part of the installation)

No further reply required - today the exact same line did work. I can just guess that Netatmo did some work yesterday …