The only thing that shouts out at me with that code is the animation speed, try setting it much higher, like 500 and trying again. That speed looks ok for a few frames of animation, but your appending about 120 frames, so your animation speed needs to be quite high.
Even if it's rediculously fast at 500, you'll know if the animation works at least and can experiment with speeds.
Personally though, I like to have all my animations in one model, means you can load it in and away you go.
Van-B

The nature of Monkey was irrepressible!.