求，foreach遍历三维数组时只能遍历出第一个子级，这是为什么呢

<br />												<tbody><br />												<?php $count=0 ;$countParent=0 ; if(isset($monitorList)){ foreach($monitorList as $key=>$val){<br />													?><br />													<tr class="treegrid-<?=$key+1+$count?>" style="cursor: pointer;"><br />														<td><?=$val['id']?></td><br />														<td title=<?=$val['name']?> onclick="task(<?=$val['id']?>,'<?=$val['name']?>')"><?=Util::msubstr($val['name'],0,16,'gbk')?></td><br />														<td><?if(!empty($val[$key])){echo count($val[$key]);}else{echo $val['product_qty'];}?></td><br />														<td><?=date("Y-m-d ",strtotime($val['date_start']))?></td><br />														<td><?=$val['plan_director_name']?></td><br />																		<br />														<td style="padding: 0px;"><br />																<span><?switch($val['status']){case 1: echo '10%';break;case 9: echo '100%';default: echo ((intval($val['status'])-1)*20).'%';}?></span><br />																<div id="progressouter" style=" border:2px solid red; height:10px; width: 64px;display:block"><div id="progressinner" style="position: relative; width:<?switch($val['status']){case 1: echo '10';break;case 9: echo '100';default: echo ((intval($val['status'])-1)*20);}?>%; height:6px; background:#23bd00;"></div></div><br />														</td><br />														<td><br />															<a style="cursor: pointer;" onclick="window.location.href='/opt_monitoring/show.candor?plan_type=<?=$val['plan_type']?>&workcenter_id=<?=$val['workcenter_id']?>&plan_id=<?=$val['id']?>'" id="show"><br />															查看</a>  <br />														</td><br />													</tr><br />										<?php 	<br />														$countParent=$key+1+$count;$child=0;<br />														if(is_array($val[$key]))foreach($val[$key] as $v){    //这里只执行了一次<br />															if($val['id']==$v['parent_id']){<br />															$count=$count+1;$child=$child+1;<br />										?><br />													<tr class="treegrid-<?echo $countParent+$child?> treegrid-parent-<?=$countParent?>"><br />														<td><?=$v['id']?></td><br />														<td><?=Util::msubstr($val['name'],0,16,'gbk')?></td><br />														<td><?=1?></td><br />														<td><?=date("Y-m-d ",strtotime($v['date_start']))?></td><br />														<td><?=$val['plan_director_name']?></td><br />														<td style="padding: 0px;"><br />																<span><?if($v['status']=='1'){echo '10%';}else if($v['status']=='9'){echo '100%';}else{ echo ((intval($v['status'])-1)*20).'%';}?></span><br />																<div id="progressouter" style=" border:2px solid red; height:10px; width: 64px;display:block"> <div id="progressinner" style="position: relative; width:<?if($v['status']=='1'){echo '10';}else if($v['status']=='9'){echo '100';}else{ echo ((intval($v['status'])-1)*20);}?>%; height:6px; background:#23bd00;"></div></div><br />														</td><br />														<td><?=$v['status']?></td><br />													</tr><br />												<?}<br />												}<br />												}}?><br />												</tbody><br />