asp使用Ajax Control Toolkit的PasswordStrength显示断言失败

使用Ajax Control Toolkit 的PasswordStrength智能提示是出现断言失败是怎么回事?
以下是我的Dome源码,麻烦各位了!!
<cc1:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server">
         
        </cc1:ToolkitScriptManager>
        <asp:TextBox runat="server" ID="txt1">   
        </asp:TextBox>  
        <asp:Label runat="server" ID="lbl"></asp:Label>
        <cc1:PasswordStrength ID="PasswordStrength1" runat="server" Enabled="true"
             TargetControlID="txt1" DisplayPosition="RightSide" StrengthIndicatorType="Text"
             PreferredPasswordLength="10" PrefixText="强度" HelpStatusLabelID="lbl"
            TextStrengthDescriptionStyles="很差;弱;一般;好;非常好" MinimumNumericCharacters="0" MinimumSymbolCharacters="0" RequiresUpperAndLowerCaseCharacters="false">            
        </cc1:PasswordStrength><br />
是使用这个的时候需要注意什么还是代码问题

[此贴子已经被作者于2017-9-23 00:57编辑过]