Resizing A Movieclip With as 2.0

i’m new to action script 2.0 and i want to create a movie clip dynamically whose position and dimensions are changed in each frame as loaded from xml;

function checkVar(row_,col_,xx_,yy_)
var col =col_;
var row = row_;
var xx = xx_;
var yy = yy_;
myButton1.x = row;
myButton1.y = col;
myButton1.buttonBkg.lineTo(yy, 0);
myButton1.buttonBkg.lineTo(yy, xx);
myButton1.buttonBkg.lineTo(0, xx);
myButton1.buttonBkg.lineTo(0, 0);
the position and dimension are changed but the problem is the last dimensions are not removed and it get bigger n bigger