Well what does this mean? It means that beyond all the creaking doors, the strange sounds, the strange activity a majority of it is natural, caused by natural occurances we just can't find. Now, we do know that alot of places are known to have paranormal activity and before making such a claim you are expected to carefully consider ALL sources and not just the picture or the strange light. If all natural things cannot be ruled out then there is a good chance your picture will be discredited.
A few common misconceptions are below...
1. Houses shift, creak, and make noises. This is more apparent in older home but it happens even in newer homes. This could account for many sounds during the night and day. If the house is new the foundation could be settling. This has been known to make very loud noises that sometimes wake others up. It can consist of groans, snaps, laughing. This has been know to happen for several months, even years if the foundation was improperly layed or rushed..
2. Is the wind blowing? Does the attic have an open window?
3. Has the family remodeled the house at all in the past year?
4. Can there be a mouse infestation in the attic? Termites? Look for evidence..
5. Has the roof been replaced recently or is it very old? Are their leaks in the ceiling?
6. Do they have pets? Do neighbors live close? Kids up in the night?
7. Is the house situated near a busy road or interstate that can be prone to sounds or shaking?
This list does not mean to check all of these things on investigations although it is a good starting point. Remember the rule of thumb.. All natural things MUST be ruled out before making a paranormal claim. Having said this, if all natural occurances are ruled out, and all tested then you may very well have paranormal activity going on. If your not sure, then perhaps you can keep the investigation open and revisit another time. If everything else is ruled out, who know.. You may have yourself a ghost!