Elasticity in mx 2004

Hey guys I have been using mx 2004 for the last couple of days,
and i wanted to do the elasticity effect but it seems not to work. Heres the formula i use on flash mx…

var k:Number = .2;
var damp:Number = .9;
var tx:Number = 300;

ax += (tx-_x)k
vx+=ax;
vx
=damp;
_x += vx;

Any ideas on how to make it work on mx 2004?