Detail view radiobutton validation

<asp:DetailsView ID="CustomersDetail" runat="server" Height="10px" Width="650px"
            DataKeyNames="customerid" OnItemCommand="CustomersDetail_ItemCommand" OnModeChanging="CustomersDetail_ModeChanging"
            AutoGenerateEditButton="True" AutoGenerateInsertButton="True"
            OnPageIndexChanging="CustomersDetail_PageIndexChanging" AutoGenerateRows="False"
            AllowPaging="True" OnItemUpdating="CustomersDetail_ItemUpdating" OnDataBound="CustomersDetail_DataBound"
            OnItemInserting="CustomersDetail_ItemInserting" CellPadding="4" ForeColor="#333333"
            GridLines="None">
<fields>
<asp:TemplateField HeaderText="Is Active?:">
                    <itemtemplate>
                        <asp:RadioButtonList ID="RadioButtonListIsActive" runat="server" RepeatDirection="Horizontal"
                           
                            <asp:ListItem Value="True" Text="Yes" />
                            <asp:ListItem Value="False" Text="No" />
                    </itemtemplate>
<fields>
<asp:DetailView></fields></fields>