Hi Guys,
I found it.
I read somewhere else that the Better Security plugin breaks the XML-RPC files and jetpack need these to work.
I have changed the security plugin to All in One WP security.
And in the tab SPAM Prevention i have to switch off the box.
If i put it on i will have problems in comments.
Thanks.
EDIT – cross-posted with you – see my post below.
Try deactivating all other plugins and switching to the twentytwelve theme to see if it’s a problem with this theme or possibly another plugin.
If it’s a plugin problem, you need to ask on the plugins own sub-forum – for JetPack here:
http://wordpress.org/support/plugin/jetpack
Find the other plugin’s sub-forums by going to the page for the plugin and clicking on the support tab.