Maybe it is in a different layer that is not rendered? https://www.blender.org/manual/render/post_process/layers.html or its rendering is disabled in the outliner https://www.blender.org/manual/editors/outliner.html
Maybe it is in a different layer that is not rendered? https://www.blender.org/manual/render/post_process/layers.html or its rendering is disabled in the outliner https://www.blender.org/manual/editors/outliner.html