Actionscripted tweening trouble

i have this code:

//setting the tween to move from 115 to 5 in 4 seconds
    var tweenPart1:Tween = new Tween(eval(_global.ticker), "_x", Strong.easeOut, _global.startPoint, _global.centreStage, _global.speed, true);

i basically moves a externally loaded image across onto the stage. the only problem is when i want to move a second image on the screen ( _global.ticker will increase by one) it still puts the first image across the stage. is there any way to refresh the variable?

Thanks
Stupid Saint