error when find div ingridview nested in datalist

I had datalist and in datalist gridview and in gridview div and I wanted to find this div I did my code but error apeared (object refrence....) here (Techgr1.Attributes.Add("Class", "ff"); )

  protected void Datalist_Categories_ItemDataBound(object sender, DataListItemEventArgs e)
    {
        Page.LoadComplete += new EventHandler(Page_LoadComplete);
        string LanguageID = Globals.GetSuitableLanguage(Page);

        if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
        {
             Techgr1 = e.Item.FindControl("TechnologyGr") as HtmlGenericControl;
       }

        GridView gridfeature = (GridView)e.Item.FindControl("grid_features");
        foreach (DataControlField column in gridfeature.Columns)
        {
            column.HeaderText = Globals.Translate(column.HeaderText, Lan开发者_开发知识库guageID);
             Techgr1.Attributes.Add("Class", "ff");
        }
}

Try this:

 protected void Datalist_Categories_ItemDataBound(object sender, DataListItemEventArgs e)
{
    Page.LoadComplete += new EventHandler(Page_LoadComplete);
    string LanguageID = Globals.GetSuitableLanguage(Page);

    if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
    {
        Techgr1 = e.Item.FindControl("TechnologyGr") as HtmlGenericControl;
    }

    GridView gridfeature = (GridView)e.Item.FindControl("grid_features");

        foreach (DataControlField column in gridfeature.Columns)
        {
            column.HeaderText = Globals.Translate(column.HeaderText, LanguageID);
            if(Techgr1 != null)
            {
                Techgr1.Attributes.Add("Class", "ff");
            }
        }

}