关于这个mkdir()的错误我没想明白

$img = array(    "./web/su.bdimg.com/static/superpage/css/../img/spis_9762e054.png",    "./web/su.bdimg.com/static/superpage/css/../img/baidu_fm_gif_72f357cc.gif",    "./web/su.bdimg.com/static/superpage/css/../img/guide_sprite_df6dde4a.png",    "./web/su.bdimg.com/static/superpage/css/../img/cite_sprite_121e6560.png",    "./web/su.bdimg.com/static/superpage/css/../img/hotnews_ac6c5b7e.png",    "./web/su.bdimg.com/static/superpage/css/../img/hotnews_ie_ca7d3ffd.png");foreach($img as $v){	$a=dirname($v);	echo $a,'<br/>';	if(!file_exists($a) && mkdir($a,0777,true)){		echo $a.'<font color="green">路径创建成功</font><br/>';	}}