Animator.Play(state) gives error

This problem is probably insanely simple, but I haven't been able to shake it. I am using Animator.Play() to perform a attack animation, the reason I am using Animator.Play as opposed to Animator.SetTrigger() is that I need the animation to be reset each time the player performs the attack.

  weaponAnimator.Play("isFiring", 0);

The above line of code gives me the warning: "Animator.GotoState: State could not be found" I tried not specifying the layer because I thought that maybe since the defult for the argument "layer" is negative the transition layer might be -1.

To be extra clear I tried this:

 weaponAnimator.Play("isFiring");

and this...

 weaponAnimator.Play("isFiring", 0, 0.0f);

Is it possible the the animation is faulty in some way? because I notice a seperate issue that the animation in game is not the same as the one in the animation preview window.