If you verify an enrolled BCID (Biometric Class ID) with an image on the BioID Playground Server you may get the result Failed even if you're really confident that the supplied image is absolutely perfect for verification.
This is often the case if one overlooks the check mark on the right of the verification page next to Live Detection. If this check mark is set – and this is the default – then the result of the verification will always be Failed if the face recognition system decides that there is no live person sitting in front of the camera. Down on the result page the message LiveDetectionFailed: The submitted samples do not prove that they are recorded from a live person will be shown also.
So how is this decision done? The face recognition system needs to have a series of images, at least 2, to calculate motion vectors in between. Then it checks whether the detected motion is typical for a human being, or whether it looks more like a photo. So this means that you must supply at least two images of your face, and there must be some movement in between. Just raise your head a bit while recording, this gives very good motion vectors!
So back to the original topic: If the LiveDetection option is check-marked, then at least two slightly different images are needed. If you supply only one, it will always fail.