宁静的班级不要访问变量，找不到符号

Question

我试图通过公共类访问公共String postForm中的String操作，但是当在public String Sum中我尝试调用optest.postForm（操作）时，它显示错误找不到符号。

using (SqlDataReader objSqlDataReader = objSqlCommand.ExecuteReader())
{
    if (objSqlDataReader.Read())
    {
        //objSqlDataReader.Close();// No longer necessary - handled by using
        objSqlConnection.Close();
        Response.Redirect("StudentExamResults.aspx");
    }
    else 
    {
        this.Master.MessageForeColor = System.Drawing.Color.Red;
        this.Master.Message = "The selected examination has not been completed.";
    }
}