Network error in mobile piwik 2 (1 reply)

I am using piwik on my server and also tried the mobile app Piwik 2 on iPhone/iPad.
Most times I log into the website because in the mobile app I receive an error regularly.
"There was an error 'The parameter 'idSite=' is missing from the request.'. The request returned the status 'HTTP/1.1 200 ok'. URL was 'http://piwik.crps-nrw.de/index.php'. Please check the entered URL....
Even removing the credentials and create a new login brings no connection.
Can you please give me a hint.
Thanks in advance.
Stefan