Publishing in Sony Vegas 8.0 Pro

[Bazzy]

So I've finished editing my video in Sony Vegas Pro 8, and was now wondering how to save it so that it will playback in Windows Media Player.
I have already tried, assuming I must use the "render as" option. So I selected my prefered format for it to save into (wmv).
But when I opened it to playback in Windows Media Player, I found that it had only rendered the middle 2 seconds of the video. Does anyone know a cause and solution for the problem? Or did I just choose the wrong option?
Thank you very much in advance!