NPC only shows after "update level"

[AlexanderK]

I use this to display windows:

PHP Code:

//#CLIENTSIDE
function onCreated() {
  this.windowtype="1b";
  this.join("window");
} 


this is the class:

PHP Code:

//#CLIENTSIDE
function onCreated() {
  this.setShape(1, 32, 32);
  showimg(200, "sorna_window"@this.windowtype@"_glass.png", this.x, this.y);
  changeimgcolors(200, 1, 1, 1, 0.7);
  changeimgvis(200, 0);
  showimg(201, "sorna_window"@this.windowtype@"_frame.png", this.x, this.y);
  changeimgvis(201, 1);
} 


When I connect to the server, the window doesn't show. It only does after I've used the update level command. I have no idea at all why this is, especially because I display the trees in the exact same way and I have no problem with them.