无法捕获WebElement的错误消息

Question

以下XPath没有捕获任何错误消息。我想在提交空白页时捕获三个错误消息。此外，声明失败。

**My code is here:**
java.util.List <WebElement> elements = dr.findElements(By.xpath("//* 
[@id='mssg_errors']")); System.out.println();          
Assert.assertTrue(elements.get(0).equals("Error message1"));
Assert.assertTrue(elements.get(1).equals("Error message2"));
Assert.assertTrue(elements.get(2).equals("Error message3"));

 **Messages are to be captured from a table:**   
  <table width="100%" border="0" cellspacing="0" cellpadding="0" 
  id="mssg_errors" name="list_errors">
   <tbody>
    <tr class="whiterow" id="field2_error" style="visibility: visible; 
     display: block;">
     <td class="contentNeg">Error message1.</td>
      </tr>
      <tr class="whiterow" id="field3_error" style="display: block; 
      visibility: visible;">
      <td class="contentNeg">Error message 3.</td>
 </tr>
  <tr class="whiterow" id="field1_error" style="display: block; visibility: 
   visible; font-weight: normal;">
  <td class="contentNeg">Error message 1.</td>
</tr>
</tbody>