PHP验证码不显示，请教如何解决

PHP验证码不显示，请问怎么解决？
http://103.246.245.147:83/joyin.php?id=joyin_LIIDSBPOQK_313333

GD库是打开的，请问验证码怎么不显示？

------解决方案--------------------

session_start();
//session_register('SafeCode');//这个函数已列于废止，使用时会有警告
$type = 'gif';
$width= 60;
$height= 20;
header("Content-type: image/".$type);
srand((double)microtime()*1000000);
$_SESSION['SafeCode'] = $randval = randStr(4,"");
if($type!='gif'&&function_exists('imagecreatetruecolor')){