I can't get this walk cycle to look the way I want it to look.

http://www.youtube.com/watch?v=rhjuv_x1gFQ

I'm working on a videogame and I've tried to make a full walk cycle of a dog. I "rotoscoped" the animation from another gif as you can see in the video. I've only animated the legs, but when I tried making the head bob and moving it butt, it looks very unnatural. I'm about to give up