Show Modal PopUp using JavaScript in ASP.Net

Hi,

For this iam using the code like this ,but no popup is arrived.

Parent page:

javascript :
 
<script language="javascript" type="text/javascript">

    function ShowPopUp(e) {
        var ReturnValue = window.showModalDialog("PopUpPage.aspx", e.paras, "dialogWidth=220px;dialogHeight=120px;scroll:no; status:no;")
        alert(ReturnValue);
    }
</script>


HTML:

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False">
    <Columns>
        <asp:TemplateField>
            <HeaderTemplate>
                Name
            </HeaderTemplate>
            <ItemTemplate>
                <asp:Label ID="Label1" runat="server" Text='<%#Eval("name") %>'></asp:Label>
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField>
            <HeaderTemplate>
                Edit
            </HeaderTemplate>
            <ItemTemplate>
                <asp:Button ID="Button1" runat="server" Text="Button" OnClientClick="ShowPopUp(this);return false;"
                    paras='<%#Eval("name") %>' />
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>

Popup Page:

<table style="width: 200px; height: 100px;">
    <tr>
        <td align="center" colspan="3">
            Modify Name
        </td>
    </tr>
    <tr>
        <td align="center">
            <asp:Label ID="Label1" runat="server" Text="Name:"></asp:Label>
        </td>
        <td>
            <asp:TextBox ID="TextBoxName" runat="server" Width="120px"></asp:TextBox>
        </td>
        <td>
            <asp:Button ID="Button1" runat="server" Text="Modify" OnClick="Button1_Click" />
        </td>
    </tr>
</table>
<script language="javascript" type="text/javascript">
    var para = window.dialogArguments;
    if (!((para == undefined || para == null) ? true : false))
        $("#TextBoxName").val(para);
    function ReturnParentPage(msg) {
        window.returnValue = msg;
        this.close();
    }
</script>

Popup code behind:

protected void Button1_Click(object sender, EventArgs e)
{
      string name = this.TextBoxName.Text;
      //your code to modify name.......
      ScriptManager.RegisterStartupScript(this, GetType(), "key", "ReturnParentPage('modify success!')", true);            
}