public virtual void Generate(Page page)
    {

        GridView grid = new GridView();
        grid.DataSource = _productsData.Tables[ 0 ];
        grid.DataBind();

        page.Controls.Add(grid);
    }

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.Web.HttpException: Control 'ctl02' of type 'GridView' must be placed inside a form tag with runat=server.

Source Error: 

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.  

<form id="form1" runat="server">