In your code you forgot _,
 
	You need the second value returned by the function which is the duration, the first being the start time so your code'll  return true in a gcd.
 
	 
 
	local _, duration = GetActionCooldown(slot) 
 
	         ^
 
	 
 
	GetActionCooldown's complete prototype is :
 
	start, duration, enable = GetActionCooldown(slot)