Asp.net 页面上的控件未根据下拉选择显示相应的值

我有一个用户注册页面，通过它可以注册新用户

如下面的ASPX页面所示，我有一个用户名下拉列表。在此下拉列表中选择任何值时，该用户的详细信息将显示在相应的控件中。这仅在用户名文本框中发生

<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">

一些附加信息

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我使用断点进行了调试，发现Password和Confirm Password包含正确的文本，但数据没有显示在各自的文本框中。我在哪里搞错了？

所以我发现如果我删除文本框控件的TextMode=“Password”属性，页面工作正常。所以我发现如果我删除文本框控件的TextMode=“Password”属性，页面工作正常。

<div>

    <table>

        <tr>
            <td class="style2">
                <asp:Label ID="lbl_UserName" runat="server" Text="User Name: " 
                    ForeColor="Black" CssClass="LabelStyles"></asp:Label>
            </td>

            <td class="style3">

                <asp:DropDownList ID="ddl_UserName" runat="server" 
                    onselectedindexchanged="UserName_Changed" AutoPostBack="True">
                </asp:DropDownList>

            </td>

        </tr>
        <tr>
            <td class="style2">
                <asp:Label ID="lbl_tbUserName" runat="server" ForeColor="Black" Text="User Name: " CssClass="LabelStyles"></asp:Label>
            </td>
            <td class="style3">
                <asp:TextBox ID="tb_UserName" runat="server"></asp:TextBox>
            </td>

        </tr>
        <tr>
            <td class="style2">
                <asp:Label ID="lbl_Password" runat="server" Text="Password: " ForeColor="Black" CssClass="LabelStyles"></asp:Label>
            </td>
            <td class="style3">
                <asp:TextBox ID="tb_Password" runat="server" TextMode="Password" 
                    ForeColor="Black"></asp:TextBox>
            </td>

        </tr>
        <tr>
            <td class="style2">
                <asp:Label ID="lbl_cnfrmPassword" runat="server" ForeColor="Black" Text="Confirm Password: " CssClass="LabelStyles"></asp:Label>
            </td>
            <td class="style3">
                <asp:TextBox ID="tb_cnfrmPassword" runat="server" TextMode="Password"></asp:TextBox>
            </td>

        </tr>
        <tr>
            <td class="style2">
                <asp:Label ID="lbl_Admin" runat="server" Text="Admin: " ForeColor="Black" CssClass="LabelStyles"></asp:Label>
            </td>
            <td class="style3">
                <asp:RadioButtonList ID="YesNo_RadioButtonList" runat="server" Height="22px" 
                    RepeatDirection="Horizontal" Width="51px" ForeColor="Black">
                    <asp:ListItem Value="1">Yes</asp:ListItem>
                    <asp:ListItem Value="0">No</asp:ListItem>
                </asp:RadioButtonList>
            </td>

protected void Populate_ddlUserName()
    {

        dsRetrieveUserDetails = objLoginData.RetrieveUser();
        dtUser.Columns.Add("UserID");
        dtUser.Columns.Add("UserName");
        dtUser.Rows.Add("", "Select User");
        dtUser.Rows.Add("Add New", "Add New");

        int count = dsRetrieveUserDetails.Tables[0].Rows.Count;

        for (int i = 0; i < count; i++)
        {
            dtUser.Rows.Add(dsRetrieveUserDetails.Tables[0].Rows[i]["UserID"].ToString() + "@" +
                dsRetrieveUserDetails.Tables[0].Rows[i]["Password"].ToString() + "@" + dsRetrieveUserDetails.Tables[0].Rows[i]["Admin"].ToString(), dsRetrieveUserDetails.Tables[0].Rows[i]["UserName"].ToString());
        }

        ddl_UserName.DataSource = dtUser;

        ddl_UserName.DataValueField = "UserID";
        ddl_UserName.DataTextField = "UserName";

        ddl_UserName.DataBind();
    }

protected void UserName_Changed(object sender, EventArgs e)
    {
        dsRetrieveUserDetails = objLoginData.RetrieveUser();

        if (ddl_UserName.SelectedItem.Text == "Add New")
        {
            //Displaying hidden controls
            lbl_tbUserName.Visible = true;
            tb_UserName.Visible = true;

            //Hiding unnecessary controls
            btn_delNo.Visible = false;
            btn_delYes.Visible = false;
            lbl_DeleteMsg.Visible = false;

            //Enabling&Disabling controls
            btn_Reset.Enabled = true;
            btn_Register.Enabled = true;
            btnDelete.Enabled = false;

            //Setting Values
            tb_UserName.Text = "";
            tb_Password.Text = "";
            tb_cnfrmPassword.Text = "";
            YesNo_RadioButtonList.ClearSelection();
        }

        else if (ddl_UserName.SelectedItem.Text == "Select User")
        {
            //Setting values
            tb_UserName.Text = "";
            tb_Password.Text = "";
            tb_cnfrmPassword.Text = "";
            YesNo_RadioButtonList.ClearSelection();

            //Disabling controls
            btn_Register.Enabled = false;
            btn_Reset.Enabled = false;
            btnDelete.Enabled = false;

            //Hiding unnecessary controls
            lbl_tbUserName.Visible = false;
            tb_UserName.Visible = false;
            lbl_DeleteMsg.Visible = false;
            btn_delNo.Visible = false;
            btn_delYes.Visible = false;
        }

        else
        {
            //Displaying some hidden controls
            lbl_tbUserName.Visible = true;
            tb_UserName.Visible = true;

            //Setting values
            tb_UserName.Text = ddl_UserName.SelectedItem.Text;

            //Enabling&Disabling controls
            btn_Register.Enabled = true;
            btn_Reset.Enabled = true;
            btnDelete.Enabled = true;

            //Hiding unnecessary controls
            lbl_DeleteMsg.Visible = false;
            btn_delYes.Visible = false;
            btn_delNo.Visible = false;

            string[] values = ddl_UserName.SelectedValue.Split('@');

            tb_Password.Text = values[1];
            tb_cnfrmPassword.Text = values[1];

            YesNo_RadioButtonList.SelectedIndex = YesNo_RadioButtonList.Items.IndexOf(YesNo_RadioButtonList.Items.FindByValue(values[2]));
        }
    }