CheckBox Greyed-Out at Advanced SQL Generation Options

Hi,
I'm trying to configure the GridView control with the SqlDataSource control. The database I specify is the built-in membership table (AspNet_MembershipUsers).

Selecting the Advanced button to bring up the "Advanced SQL Generation Options", it shows both checkbox options greyed-out and so I can't do an Insert, Update or Delete operations.

    <form id="form1" runat="server">
    <div>
        <asp:GridView ID="GridView1" runat="server" AllowPaging="True"
            AllowSorting="True" AutoGenerateColumns="False" DataKeyNames="UserId"
            DataSourceID="SqlDataSource1">
          ...