Audio source problem

I have this

var clip : AudioClip;

function Update () { if( Input.GetButtonDown("w") ) { audio.Play(AudioClip);

}
}

but unity says: no appropriate version of unityengine.audiosource,...

what do i need to do??

Change to:

audio.PlayOneShot(clip);

You're using the type instead of the variable. Should be just "audio.Play()", and assign the clip using "audio.clip = clip".