Illegal use of <when>-style tag without <choose> as its direct parent

在jsp页面用报错Illegal use of <when>-style tag without <choose> as its direct parent
原因是：必须在里面使用。
具体用法如下：

<c:choose>
    <c:when test="${book.compareToday==‘0‘}">
    <h5>预约过期</h5>   
    </c:when>   
    <c:otherwise>
取消预约
</c:otherwise>
</c:choose>