Ajax Calendar control not showing properly in Gridview Footer template.

Question

I am not getting full view of Ajax Calendar control in gridview Footer template.

The last column date in the date picker, not showing properly.

Friday and saturday is hiding and not showing properly.

<asp:TextBox ID="txtDOB" CssClass="txtInput" ReadOnly="true" runat="server" Text=""></asp:TextBox>
                               <ajaxToolkit:CalendarExtender ID="CalendarExtender1" runat="server" TargetControlID="txtDOB"
                                      Format="MM/dd/yyyy" OnClientDateSelectionChanged="CheckDateEalier" PopupButtonID="btnDate1"
                                      PopupPosition="BottomRight" CssClass="cal_Theme1"></ajaxToolkit:CalendarExtender>
                                        <asp:ImageButton ID="btnDate1" ImageUrl="~/images/imgCalendar.png"
                                            runat="server" />