CalendarExtender does not popup

Hi,

I have a CalendarExtender which does not pop up the calendar.

I have another Calendar Extender on the same page which works as expected.

Why is the first control not popping up the calendar. I do not see anything wrong with the properties of the control.

<asp:TextBox ID="txtDate" runat="server" CssClass="txt"></asp:TextBox><asp:RequiredFieldValidator ID="requiredDate" runat="server" ErrorMessage="Please Enter From Date." ValidationGroup="Add"
                    ControlToValidate="txtDate">*</asp:RequiredFieldValidator><asp:CompareValidator ID="CompareDate" runat="server" ErrorMessage="Please enter Date in MM/dd/yyyy format."
                    ControlToValidate="txtDate" ToolTip="Please enter date in MM/dd/yyyy format." ValidationGroup="Add"
                    Operator="DataTypeCheck" Type="Date" SetFocusOnError="true">*</asp:CompareValidator><asp:CalendarExtender runat="server" ID="CalenderExtender3" Format="MM/dd/yyyy" TargetControlID="txtDate" ></asp:CalendarExtender>

<asp:TextBox ID="txtFromDt" runat="server" CssClass="txt"></asp:TextBox><asp:RequiredFieldValidator ID="requiredFromDt" runat="server" ErrorMessage="Please Enter From Date."
                                ControlToValidate="txtFromDt">*</asp:RequiredFieldValidator><asp:CompareValidator ID="CompareFromDate" runat="server" ErrorMessage="Please enter Date in MM/dd/yyyy format."
                                ControlToValidate="txtFromDt" ToolTip="Please enter date in MM/dd/yyyy format."
                                Operator="DataTypeCheck" Type="Date" SetFocusOnError="true">*</asp:CompareValidator><asp:CalendarExtender ID="CalendarExtender1" runat="server" Format="MM/dd/yyyy"
                                TargetControlID="txtFromDt"></asp:CalendarExtender>

Thanks in Advance