Poor contacts are always a big problem with low voltage D.C. a) because voltage = 'pressure' and any limited resistance [i.e. dirty contacts within the camera or on the batteries] will impede the flow of electrical current, and b) direct current tends to 'plate' any metal connections/contacts [read: fur them up]. So - thoroughly clean all connections with Isopropyl Alcohol. Also [as mentioned by others] gently re-tension the camera battery bay contacts and if possible fit a small pad of very thin foam rubber underneath each. I did this with my Fujifilm A700 [which has been annoying me for ages] and it's been fine ever since.