I don't know how to tell it in Englisch, but the error "came out of nothing". I've put the source and the trace in the attach file.

[Warning] curl_setopt() [function.curl-setopt]: CURLOPT_FOLLOWLOCATION cannot be activated when in safe_mode or an open_basedir is set
GET /foto-s/

Line 103 in /home/dirk/domains/meifeest.com/public_html/sapphire/api/RestfulService.php

Is it something with the API i have?

This error will only appear when you're running in dev mode. It is because your host has open_basedir enabled, which is restricting the usage of certain curl options that the Flickr module is using.

To fix this, you could either comment out line 103 in sapphire/api/RestfulService.php or get open_basedir disabled. If you're on a shared host, the former will be the easiest as most hosts will be unwilling to disable open_basedir.

hmm, I've put Director::set_environment_type('live'); in _config.php but I still get that error.