Code on frame moving object

for(x=1;x<=9;x++){
**["txt"+Number(x)]._x** = parseInt(this["textx"+Number(x)]);
}

Flash gives me an error when i try to run this on a frame (its in load text things) it works when i looks like this.

txt1._x = parseInt(this.textx1);

the bolded part that is changed in the top is whats wrong.