254368 ffmpeg problem

I have a custom ffmpeg script which worked like a charm on my previous host. since i have shifted host, it does not work. It creates the thumbnails and everything but the output .flv is 0 bytes. I want you to diagnose if the problem is with script or ffmpeg setup on server. If you are good with ffmpeg, Ask me for log file of video conversion at PMB so that you can diagnose the problem.