类型转换错误(求助)

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            e.Row.Attributes.Add("onmouseover", "c=this.style.backgroundColor;this.style.backgroundColor='#eeeeee'");
            e.Row.Attributes.Add("onmouseout", "this.style.backgroundColor=c");
            ((Button)e.Row.Cells[4].Controls[0]).Attributes.Add("onclick", "javascript:return confirm('你确认要删除：\"" + e.Row.Cells[0].Text + "\"吗?')");   //就是这句有错误说无法将类型为“System.Web.UI.LiteralControl”的对象强制转换为类型“System.Web.UI.WebControls.Button”
     }
    }
请高手帮我解决一下