For + array + property + variable = trouble

1

i´m doing a loop to attribute the values to _x property, and use it to make random movimets with movieclips
i´ve got 16 movieclips in my stage, named
b1, b2, b3…b16

and the code is

count = 0
chama = setInterval(function () {
 count++
 for (a=1; a<=16; a++) {
  eval("b"+a).xp = random(68)+11
  eval("b"+a).yp = random(68)+11
   eval("b"+a).onEnterFrame = function() {
	this._x =  this._x + (this.xp-this._x)/10
	this._y += (this.yp-this._y)/10
   if (_root.count == 3) {
	clearInterval(chama)
	setInterval(cPos, 1000)
}
 };
}
},2000)

so… after 3 time that setinterval execute this function, i´d like to call a function to get this movieclips, in their current positions and take them in especifics positions on stage

so I created an Array and I´m trying to use this code to define variables with values from the Array, and make a moviment to the especifics positions

xC = [63.9, 16.95, 45.85, 65.55, 18.75, 26.2, 55.85, 55.25, 28.85, 21.95, 36.6, 35.75, 14.7, 45.7, 14.45, 60.75]

function cPos () {
for (a=1; a<=16; a++) {
   eval("b"+a).onEnterFrame = function() {
	 this._x =  this._x + (_root.xC[a+1]-this._x)/10
	 
  
   }
  }
}

but it´s not working

why???

what can I do to Take the variables inside the array and use them to respectives movieclips b1, b2…b16???

thanks
Chan