change the ai to dark ai.
or change the actual speeds of the zombies, and actualy go into the scripts and have a tinker, you can change the anim frames etc. it takes a lot of tinkering, but if you are persistant and really want them to work, have a dabble. i know they worked when i changed the speed and part of the scripts but i not used them onlt toyed when purchased, but in the develpoment i had reached progress was made so i wish you happy tinkering, when i do get the opportunity to dabble i will give you all my findings, alas though this could be months
an unquenchable thirst for knowledge of game creation!!!