Strange Player7 behavior

I have this on button:


on (release) {
 _parent.sizer = "big";
 _parent.thumbnailer = this._name;
 _parent.thumbnailer_id = id;
 _parent.initialize_position(this._name, id);
 _parent.picture = "picture_big";
 _parent.square_script.gotoAndPlay(2);
 trace (_parent.sizer)
 trace (_parent.thumbnailer)
 trace (_parent.thumbnailer_id)
 trace (_parent.initialize_position(this._name, id))
 trace (_parent.picture)
 trace (_parent.square_script)
}

Trace action gives this back:

big
button_namer_1
1
undefined
picture_big
_level0.mainclip.square_script

The “undefined” function is:

// --------------------------------------------------
// initialize function
// --------------------------------------------------
function initialize_position(picture,picture_id) {
 counter = 1;
for (j = 1; j<=total_y; j++) {
 for (i = 1; i<=total_x; i++) {
   increment_x = this[picture]._width/4;
   increment_y = this[picture]._height/4;
   this["square_mask_" + counter]._x = i*increment_x - increment_x + this[picture]._x;
   this["square_mask_" + counter]._y = j*increment_y - increment_y + this[picture]._y;
   this["square_mask_" + counter]._xscale = increment_x;
   this["square_mask_" + counter]._yscale = increment_y;
   this["square_mask_" + counter]._alpha = 100;
   this["square_mask_" + counter].picturedata._x = i*-increment_x*4 + increment_x*4;
   this["square_mask_" + counter].picturedata._y = j*-increment_y*4 + increment_y*4;
   this["square_mask_" + counter].picturedata.gotoAndStop(picture_id);
   counter++;
  }
 }
}
initialize_position("picture_1",1);

Why the Flashplayer6 has no problems with and the Flashplayer7 does not execute the release action?
Thanks for suggestions.