Calendar Extender Issues

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:

Below is my css for the calendar