[phpBB2]  Probleme mit dem wechsel-Header

while(true){
aleatorio = Math.random();
numero = Math.round(aleatorio * 5);

if (numero == 0){
imagen = "https://2img.net/r/ihimg/photo/my-images/5/xwv.png/";
break;}

if (numero == 1){
imagen = "https://2img.net/r/ihimg/photo/my-images/405/m6d.png/";
break;}

if (numero == 2){
imagen = "https://2img.net/r/ihimg/photo/my-images/191/zs6u.png/";
break;}

if (numero == 3){
imagen = "https://2img.net/r/ihimg/photo/my-images/198/rcp.png/";
break;}

if (numero == 4){
imagen = "https://2img.net/r/ihimg/photo/my-images/689/uveu.png/";
break;}

if (numero == 5){
imagen = "http://tinypic.com/r/2rxb09e/5";
break;}
}
document.write('<a href="http://touhou-rpg.forumieren.net" target="_self"><img src="' + imagen + '" style="width: 720px; height: 90px" border="0"></a>');