Rendering image sequence repeats first frame

Reality Hack

Hi. I'm trying to render an image sequence using OpenGL (it doesn't make a difference if I use Basic or Intermediate) but although the indicator moves across the timeline, it just renders the first frame over and over. Rendering to a movie just produces a black movie. I thought I solved this before. I thought it had something to do with the naming convention containing spaces or something like that, but now that's not working. Any help would be appreciated. Thanks.