Thank you, Your Mother. I certainly gave too little details. I solved the issue. MySQL was set correctly. I was passing the values with a GET and something like this: /cgi-bin/mobile/setNewAccount.pl?key=$LicenseKey&user=$CloudUserName&pw=$CloudUserPW This would have needed special care for special characters. So I simply switched to POST and sending my data with:
my $request = POST($url, Content_Type=>'application/json',
Content => encode_json($data) );
my $response = $ua->request($request);
This works fine. Will now read on vulnerabilities of this approach.