"The usual cause of this problem is you begin a clip and add models to it and start animating.

You hit that wonderful 60 second mark and decide to extend the clip and the shot.

You start animating at around 60 seconds into the clip and find the model stops moving.

When you spawn the model, SFM looks at the slip size and creates an animationset channel for everything you spawn giving the channel around 5 extra second past the end ot time of the clip (65 Seconds is the default if the clip and shot is not amended before the spawn.).

The problem is that the aniSetEditor Channels aren't tried to the time line and doesn't change when the clip/shot is extended. If you spawn something to the clip before editing it, you have to manually extend the aniSetEditor channel for every element in the in the animation set editor in order to animate it after that 65 second mark.

You get into the aniSetEditor Channels editor by double clicking the clip from the Clip Editor."