AJAX+.NET实现会员注册中的问题~!
1.首先在web.config中配置好
<httpHandlers>
<add   verb= "POST,GET "   path= "ajax/*.ashx "   type= "Ajax.PageHandlerFactory,   Ajax "   />
</httpHandlers>

2.
private   void   Page_Load(object   sender,   System.EventArgs   e)
{
Ajax.Utility.RegisterTypeForAjax(typeof(clsValdate)   ,this);
}
3.
internal   class   clsValdate
{
[Ajax.AjaxMethod]
public   string   ValidateInput(string   userName)
{
string   su   =   "xxx ";
                                    //可以在这里操作．
string   retVal   =   "用户不存在，可以使用！ ";

if(userName.Equals(su))
retVal   =   "用户名已存在，请选用其它用户名 ";

return   retVal;
}
}

4.
<script   language= "javascript "   type= "text/javascript ">
function   ValidateInputData()
{
var   txt   =   document.all[ "txtUserName "];

if(txt.value   ==   " ")
{
Show( "用户名不能为空 ");
return   false;
}

var   _value   =   clsValdate.ValidateInput(txt.value).value;
if(_value   !=   null)
{
Show(_value);
}

return   true;
}

function   Show(message)
{
var   objMessage   =   document.all[ "spMessage "];
objMessage.style.display   =   " ";
objMessage.innerText   =   message;
}
</script>
5.
<table   width= "450 "   align= "center "   cellpadding= "2 ">
<tr>
<td   colspan= "2 "   height= "20px "   align= "center "> <span   id= "spMessage "   style= "display:none; "   class= "ms "> </span> </td>
</tr>
<tr>
<td   align= "right "> 用户名 </td>
<td>
<asp:TextBox   id= "txtUserName "   onblur= "return   ValidateInputData(); "   runat= "server "   CssClass= "tb "> </asp:TextBox> </td>
</tr>
<tr>
<td   align= "right "> 密码 </td>
<td>
<asp:TextBox   id= "TextBox2 "   runat= "server "   CssClass= "tb "> </asp:TextBox> </td>
</tr>
<tr>
<td   align= "right "> 确认密码 </td>
<td>
<asp:TextBox   id= "TextBox3 "   runat= "server "   CssClass= "tb "> </asp:TextBox> </td>
</tr>
<tr>
<td   colspan= "2 "   align= "center ">
<asp:Button   id= "btnSubmit "   runat= "server "   Text= "Submit "   CssClass= "tb "> </asp:Button> </td>
</tr>
</table>

按以上设置以后,实现检测用户和判断是否为空都正常,在按钮的事件中实现插入数据的时候,都是错的,也会提示插入成功,这要怎么解决???

------解决方案--------------------
<asp:TextBox id= "txtUserName " onblur= "return ValidateInputData(); " runat= &quo