pbootcms模板文章列表没有缩略图时也不显示默认图片

{pboot:list scode={sort:scode}}
    <a href="[list:link]" rel="external nofollow"  title="[list:title]">
    <div class="flex-column">
        {pboot:if('[list:isico]'=='1')}
        <img src="[list:ico]" alt="[list:title]">
        {/pboot:if}
        <div class="text-box">
        <h4>[list:title]</h4>
        <p class="intro hidden-sm">[list:content drophtml=1 dropblank=1 lencn=120]</p>
        <p><span><i class="fa fa-clock-o" aria-hidden="true"></i> [list:date style=Y-m-d]</span><span><i class="fa fa-eye" aria-hidden="true"></i> list:visits 浏览</span><span><i class="fa fa-thumbs-up" aria-hidden="true"></i> list:likes 点赞</span></p>
        </div>
    </div>
    </a>
{/pboot:list}

{pboot:if('list:isico'=='1')}
        <img src="[list:ico]" alt="[list:title]">
{/pboot:if}