クラスメソッドの戻り値、不思議な現象の解決策

	public function accountTreeType1($arrData){<br />
<br />
		$this->strLable = $this->strLable.'<ul>';<br />
<br />
		foreach($arrData as $val){<br />
<br />
			if(is_array($val['child'])){<br />
				$this->strLable = $this->strLable.'<li>'.$val['acc_code'].$val['acc_name'];<br />
				$this->accountTreeType1($val['child']);<br />
			}else{<br />
<br />
				$this->strLable = $this->strLable.'<li>'.$val['acc_code'].$val['acc_name'].'</li>';<br />
                                 if($val[id]=='最后一个ID')｛<br />
                                      return $this->strLable; //在这里没有返回值，不过用echo $this->strLable;是可以打印出来，但是返回值为空。<br />
                                 ｝<br />
<br />
			}<br />
<br />
		}<br />
<br />
		$this->strLable = $this->strLable.'</ul>';<br />
<br />
	}