Scrolling based on Mouse x location

lets say I have a movie with dimensions of width 300, height 400
and i have a MC with a width of 600, centered on the movie…
I’m trying to scroll it to the left and right, with boundries using this AS on the MC.

[AS]
onClipEvent(enterFrame) {
// move right
if((_root._xmouse >= 200)and this._x >= 0) {
this._x +=5;
}
// move left
else if((_root._xmouse <= 100)and this._x <= -300) {
this._x -=5;
}
}

[/AS]

but it doesn’t quite work right, the boundries are wrong, can anyone correct that for me?