why my Gridview disappeared after using selecting query?

<asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server">
</asp:Content>

<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
    <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False"
         DataSourceID="AccessDataSource1" >
        
        <Columns>
            <asp:BoundField DataField="USER_NAME" HeaderText="USER_NAME" SortExpression="USER_NAME" />
            <asp:BoundField DataField="COURSE_CODE" HeaderText="COURSE_CODE" SortExpression="COURSE_CODE" />
            <asp:BoundField DataField="COURSE_NAME" HeaderText="COURSE_NAME" SortExpression="COURSE_NAME" />
        </Columns>
    </asp:GridView>
    <asp:AccessDataSource ID="AccessDataSource1" runat="server" DataFile="~/App_Data/ASPNetDB.mdb" 
        SelectCommand="SELECT * FROM [studentenrolled] WHERE ([User_name] = ?)">
      
        <SelectParameters>
            <asp:SessionParameter Name="User_name" SessionField="User_name" />
        </SelectParameters>
    </asp:AccessDataSource>
</asp:Content>