Calendar Extender Issues

Question

 

 

The image above shows the error...I lost the Saturday! Can someone assist me on how to fix this? Below are the markup and css

<asp:TemplateField HeaderText="Birthday">
                            <ItemTemplate>
                                <asp:TextBox ID="txtFamilyDOB" runat="server" Style="padding: 0; " CssClass="form-control" AutoCompleteType="Disabled">asp:TextBox>
                                <ajaxToolkit:CalendarExtender ID="txtFamilyDOB_CalendarExtender3" runat="server"
                                    TargetControlID="txtFamilyDOB"
                                    PopupPosition="BottomRight"
                                    CssClass="MyCalendar"
                                    Format="dd/MM/yyyy" BehaviorID="txtFamilyDOB_CalendarExtender3" />
                                <asp:RequiredFieldValidator ID="RequiredFieldValidator2" runat="server" ControlToValidate="txtFamilyDOB"
                                    ErrorMessage="*" SetFocusOnError="True" Font-Bold="true" ForeColor="Red">asp:RequiredFieldValidator>
                            ItemTemplate>
                            <ItemStyle Font-Size="7pt" />
                        asp:TemplateField>

 The Gridview has the following css:

.responsiveTable {
            overflow-x: auto;
        }

Below is my css for the calendar 

.MyCalendar .ajax__calendar_container {
            border: 1px solid #646464;
            background-color: lemonchiffon;
            color: red;
        }