there is a possibilty your camera limits are too small/too large. If you select your camera and open the attrritube editor (ctrl+a by default) adjust the value of the far clip plane to say 1000000 and see if you get any positive results. Clip planes can cause all kinds of viewport errors especially ones that you won't see in the perspective as you are constantly moving around in that one and sit in most cases closer than any of the other cameras.