In Unity 4, there are two ways to invoke model animation.
The "classic" way, as in Unity 3: When importing fbx, you must set the "animation type" under "Rig" to "legacy". In Hierachy, a model needs an Animation component, not an Animator component! Then you need to add the animation from your model to the animation component. Now you can write
animation.Play("Idle");
"New" mechanism: When importing fbx, you should set the "animation type" under "Rig" to "generic". In Hierachy, a model needs an Animatior component, not an Animaton component! Then you have to add the animation from your model to the animation controller that you add to the Animator component. In the controller, you can set values ββto switch between different animations. But if you want to use Mechanim, look at this tutorial, it helped me a lot!
http://www.youtube.com/watch?v=Xx21y9eJq1U
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