n00b cant get startdrag to work

here is the code… but i just want the movie to remain in the center of the flash movei without moving into the top left hand corner… the x y are at the exact spot i want the animation to stay at untill someone clicks the flash… but its keeps moving to the top left hand corner…can someone help me out please… thanks… Zoo

onClipEvent (load) {
_x = 236;
_y = 30;
speed = 5;
onClipEvent (mouseDown) {
endX = _root._xmouse;
endY = _root._ymouse;
onClipEvent (enterFrame) {
_x += (endX-_x)/speed;
_y += (endY-_y)/speed;