Why does no picture show no thumbnail?

Question

<td>
   <if condition="$vo.['pic'] neq ''">
      <img src="__ROOT__{$vo.pic}"height="50">
       <else />
        无缩略图
   </if>
</td>

Answer 1

There is no dot after vo in the if condition line

Answer 2

firebug, check if the image address obtained is correct

Answer 3

See if the data has been obtained