php - Using simplehtmldom to grab a text snippet -

i'm trying use simplehtmldom script @ text. html structure follows

<div id="posts">   <div align="center">     <several levels of html>       <strong>xxx</strong>     </several levels of html>   </div>   <div align="center">     <several levels of html>       <strong>ignore</strong>     </several levels of html>   </div>   <div align="center">     <several levels of html>       <strong>ignore</strong>     </several levels of html>   </div> </div> 

the text i'm trying @ xxx string, in first <strong> tags inside first <div> attribute align="center", inside <div> id="posts". i'm not interested in text in <div align="center"> tags further down.

the "several levels of html" include messy nested tables etc.

my code: i'm using descendant selectors , i'm "skipping" through several levels of html. reason why print_r shows "trying property of non-object"?

$html = file_get_html($page_1); $es = $html->find('div#posts div[align=center] strong'); print_r($es->plaintext); die; 

strangely enough statement returns same "trying property of non-object" result. doing wrong?

$es = $html->find('div#posts'); 

2 possible reasons :

1. in $html = file_get_html($page_1);, $page_1 may not url. if it's string containing html use str_get_html in $html = str_get_html('<div id="hello">hello</div><div id="world">world</div>'); instead.
2. the html contains more 1 div#posts (which shouldn't).