pbootcms列表置顶文章istop无效的解决方法

{pboot:list istop=1}
<article>
<h2>{content:title}</h2>
<p>{content:description}</p>
<a href="{content:link}">阅读全文</a>
</article>
{/pboot:list}

{pboot:list num=8 order='istop desc,sorting asc,date desc,id desc'}
<article>
<h2>{content:title}</h2>
<p>{content:description}</p>
<a href="{content:link}">阅读全文</a>
</article>
{/pboot:list}