Problem With Footsteps

[Popper99]

I've made a robot using the basic biped skeleton and changed the structure a bit (5 fingers and 1 spine). I then used the select and link tool to assign the arms to the skeleton's arms, legs, etc. I now want to use footsteps but the option remains gray and unusable. It works with other bipeds but not this one. It also worked just fine when I had only assigned the arms to the skeleton. Maybe I accidentally pressed some key combination (There are green squares highlighting the ends of joints that just randomly appeared)? Any help would be appreciated