I need help with animation script

Hello, I need to reproduce an animation of a certain Game Object when the mouse is down over other GameObject,
but the problem is that I need taht on the time when the mouse is down , first reproduce an especific animation and then when it finish reproduce other and the second one have to loop all the rest of the time that the mose is down, and when de mouse is up it have to reproduce an other specific anitamtion…I do the following script but I have the problem when the first animation start to reproduce and the mouse is up it reproduce the "normal"animation and then return to the “eatChicken” animation and I need that stop on the normal and active the anmations when the mouse is down again, Someone could help me ? I hope that I explained me correctly , and sorry about my english.

var David:GameObject;

function OnMouseDown () {

if (!David.animation.isPlaying){
David.animation.Play(“eating”);
yield WaitForSeconds(David.animation[“eating”].length);
David.animation.Play(“eatChicken”);
}
}

function OnMouseUp(){

David.animation.CrossFade(“normal”);

}

thanks

thanks , I resolved this con animation events