ffmpeg -t doesn't conversion section of WMV, converts whole video

Question

I'm trying to run the command:

./ffmpeg -ss 0.0 -t 1 -y -i Wildlife.wmv  output.mpg

to convert the first second of the WMV video, but it converts the whole 30 seconds of the video. Am I doing something wrong? I've tried changing the order ot -ss and -t, but it always converts the whole 901 frames.