Animation CrossFade not working

I re-read the Character Animation guide and I simply fail to understand why my script isn't working!

Activate is called every frame when the mouse is down, and deactivate is called every frame when the mouse is up...

function Activate() {
if (!animation.IsPlaying("activate"))
    {
    animation.CrossFade("activate");
    }
triggerThis.Activate(); //a check to see if the function calls
}

function Deactivate() {
if (!animation.IsPlaying("deactivate"))
    {
    animation.CrossFade("deactivate");
    }
triggerThis.Deactivate(); 
}

Both "activate" and "deactivate" are animations in my Animation pane for the object.

Animations
    Size:     2
    Element 0:activate
    Element 1:deactivate

My script should theoretically check if its respective animation is playing. If it's not, play the animation. If it is playing, ignore it.

When I run the game, and click, the Activate script is run, but there's no animation!

Can anyone shed some light on this for me?

Thank you!

Replacing CrossFade with Play worked

Peter