I was unable to go previous month and next month by clicking the next and previous.
And i also unable to display another color when i selected a date.

<asp:Calendar ID="cldDOB" runat="server" BackColor="#FFFFCC" BorderColor="#FFCC66" BorderWidth="1px" DayNameFormat="Shortest" Font-Names="Verdana" Font-Size="8pt" ForeColor="#663399" Height="200px" ShowGridLines="True" Width="220px" NextPrevFormat="ShortMonth">
                                        <DayHeaderStyle BackColor="#FFCC66" Font-Bold="True" Height="1px" />
                                        <NextPrevStyle Font-Size="9pt" ForeColor="#FFFFCC" />
                                        <OtherMonthDayStyle ForeColor="#CC9966" />
                                        <SelectedDayStyle BackColor="#CCCCFF" Font-Bold="True" />
                                        <SelectorStyle BackColor="#FFCC66" />
                                        <TitleStyle BackColor="#990000" Font-Bold="True" Font-Size="9pt" ForeColor="#FFFFCC" />
                                        <TodayDayStyle BackColor="#FFCC66" ForeColor="White" />


When i press the textbox and it does display the calendar as well as display the selected date on textbox,
but the calendar is display on the top?
P/S: This is the slider menu.

Sounds like a styling issue at this point. Have you tried to reposition the calendar by using position, left, right, etc..?

ya i did tried reposition, but it still the same showing at the top. :/

Do you have this site online to take a look? or recreate the HTML related code? The positioning shouldnt be related to asp.net. Its more of a styling problem you are having now.

In another pages i do have apply this and it work fine with the position.
Only this page seem out of positioning.
This project is created for my Final Year, thus i don't upload to online.
If you wish to take a look, i may email to you?

You can zip up the file and upload via a post if its too large to post the relevant code.

The File Type is invalid.

                                    <asp:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server" />      
                                    <asp:Label runat="server" Text="Date of Birth: " />                                                                  
                                    <asp:TextBox ID="txtDOB" runat="server" />
                                    <asp:CalendarExtender runat="server" TargetControlID="txtDOB" TodaysDateFormat="d MMMM, yyyy" Format="dd/MM/yyyy" /> 
                                    <asp:RequiredFieldValidator runat="server" ErrorMessage=" *" ControlToValidate="txtDOB" ForeColor="Red" ValidationGroup="ValidateRegister" Font-Size="10pt" /> 

there are much more label and textboxes before and after than these.

I'm not going to be able to reproduce it based on what you just posted. sorry about that.

I think that should my GUI affected this problem. :o
Due to my page is a slider menu, thus all sub menu content are enclosed.
I try to redesign my interface, the problem would be solve. :)
Thanks btw.