如此奇怪的问题，高分求解，关于DOM的

phpinfo（）显示：
    146 dom
    147
    148 DOM/XML => enabled
    149 DOM/XML API Version => 20031129
    150 libxml Version => 2.7.3
    151 HTML Support => enabled
    152 XPath Support => enabled
    153 XPointer Support => enabled
    154 Schema Support => enabled
    155 RelaxNG Support => enabled但是我的程序：
    $t = new DOMDocument();
却报错：   Fatal error: Class 'DOMDocument' not found in /web/....