404. That’s an error.
The requested URL /add?source=atgs&feedurl=http%3A//vliegvisgroeptheleader.nl/index.php%3Foption%3Dcom_ninjarsssyndicator%26feed_id%3D3%26format%3Draw was not found on this server. That’s all we know.
/add?source=atgs&feedurl=http%3A//vliegvisgroeptheleader.nl/index.php%3Foption%3Dcom_ninjarsssyndicator%26feed_id%3D3%26format%3Draw