Have you tried to change the action to something like:
<karen>-set animation to "WALK"
If so maybe try to make a global variable
Ex:
global variable "movement" = 0
<karen>-on platform move- - <system>- "movement" set value to 1-
else -set "movement" to 0-
<system>-compare variable "movement" = 1-<karen>-set animation to "WALK"-