Basic Rendering Question

(Blender 2.46) I have a 50x50 plane, extruded the two sides and back by 50, subdivided it so I have an open box. When I render it (F12) with the camera at a distance to try to see the whole thing, the back wall disappears, if I postion it close, it reappears.
Anyone know why this is the case and how I can work around this?

Could be the clip distance of the camera, right?

Select the camera, press F9 and try to extend the distance. That might be it.

Got it. Thanks.