Capture frame from a mpg file

[fr33d0m]

Hi, i'm having problem here.
I'm unable to capture frame from a mpg file.
I'm using this command : convert 1185644451_21286.mpg[58] output.jpg
And the result is : convert: missing an image filename `output.jpg'.
Can someone guide me, pls?
Thanks in advance

[anthony]

Sure the file has 59 frames in it? remember frame numbers count from zero.
Also check that IM can read that specific type of animation.