i have included this code in my ArticlePage as

function LatestNews($num=5) {
$news = DataObject::get_one("ArticleHolder");
return ($news) ? DataObject::get("ArticlePage", "ParentID = $news->ID", "Date DESC", "", $num) : false;
}

and

<ul id="NewsList">
<% control LatestNews %>
<li class="newsDateTitle"><a href="$Link" title="Read more on &quot;{$Title}&quot;">$Title</a></li>
<li class="newsDateTitle">$Date.Nice</li>
<li class="newsSummary">$Content.FirstParagraph<a href="$Link" title="Read more on &quot;{$Title}&quot;">Read more &gt;&gt;</a></li>
<% end_control %>
</ul>

in ArticlePage.ss but in front end article page it is not showing the news detail

please help

The method DataObject::get_one() returns only one DataObject.
I would try to get out what the controller method really returns with Debug:log()