Struts Problem Report

<select name="stoInoutListSearch.discountAmount" id="discountAmount">
  <option value="" selected="selected">请选择</option>
<option <c:if test="${stoInoutListSearch.discountAmount=='有'}">selected="selected"</c:if>value="有">有</option>
  <option <c:if test="${stoInoutListSearch.discountAmount=='无'}">selected="selected"</c:if>value="无">无</option>
  </select>




Struts Problem Report
Struts has detected an unhandled exception: 

Messages: No result defined for action cn.cisp.storage.actions.SellOutStorageAction and result input 
 
File: file:/D:/workspace3.6/.metadata/.plugins/org.eclipse.wst.server.core/tmp0/wtpwebapps/ERP/WEB-INF/classes/struts.xml 

action里面执行的方法没有返回值