Set Position of AJAX CalendarExtender in ASP.Net

while i am using Ajax (calender extender) on textbox

when i click at first time click

the calender show on page top side

next time show on textbox side correctly.

<asp:CalendarExtender ID="CalendarExtender4" TargetControlID="txtfrm_date" Format="d/MM/yyyy"
                                        runat="server">
                                    </asp:CalendarExtender>
                                    <asp:FilteredTextBoxExtender ID="FilteredTextBoxExtender3" runat="server" TargetControlID="txtfrm_date"
                                        FilterType="Custom,Numbers" ValidChars="/">
                                    </asp:FilteredTextBoxExtender>