Some of your events are conflicting with each other. For example, you have a "Key S is down" event and a "Key S is down AND Key D is down" event, both of which can be true at the same time. You need to add additional checks to some of the events to see whether certain keys are NOT down. Here's a fixed CAP:
Fixed Walking Animation
The changed events are commented and bookmarked so you know which ones received changes.
Hope this helps.