C# FreeTextBox的RequiredFieldValidator和RegularExpressionValidator在2个位置显示错误消息

在我的aspx页面中：

<table cellpadding="2" cellspacing="2" align="center">
<tr>
  <asp:ValidationSummary ID="Alert" runat="server" CssClass="failureNotification" HeaderText=""/>                                  
</tr>

 <tr>
   <FTB:FreeTextBox id="FTB" runat="server"/>
  <asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ControlToValidate="FTB" CssClass="failureNotification" ErrorMessage="Content cannot be empty." ToolTip="Content cannot be empty." ></asp:RequiredFieldValidator> 
  <asp:RegularExpressionValidator ID="rev" runat="server" ControlToValidate="FTB" ErrorMessage="Text with only spaces is not allowed." ToolTip="Text with only spaces is not allowed "  ValidationExpression="[^\s]+" CssClass="failureNotification"/>                      
 </tr>
</table>

我正在为FreeTextBox FTB使用1个RequiredFieldValidator和1个RegularExpressionValidator

当我将FreeTextBox清空时，RequiredFieldValidator的错误消息显示在两个位置：

当我在FreeTextbox中只按空格键时，RegularExpressionValidator的错误消息也是如此

注：RequiredFieldValidator有2个职位，RegularExpressionValidator也有2个职位。两个位置都不是2

救命啊！！！我只想在1个位置显示错误消息：在表的顶部