.net Console.WriteLine 未显示在输出窗口中

我已经输入了大约Console.WriteLine个调用进行测试，但它们没有出现在输出框中？

public static ArrayList myDeliveries = new ArrayList();

public mainForm(){
    InitializeComponent();
}

private void mainForm_Load(object sender, EventArgs e){

    if (!File.Exists("../../MealDeliveries.txt")){
        MessageBox.Show("File not found!");
        return;
    }

    using (StreamReader sr = new StreamReader("../../MealDeliveries.txt")){
        //first line is delivery name 
        string strDeliveryName = sr.ReadLine();
        Console.WriteLine("Test content");

        while (strDeliveryName != null){

            //other lines 
            Delivery d = new Delivery(
                strDeliveryName, 
                sr.ReadLine(),
                sr.ReadLine(), 
                sr.ReadLine(),
                sr.ReadLine(), 
                sr.ReadLine(),
                sr.ReadLine()
            );

            mainForm.myDeliveries.Add(d);

            //check for further values
            strDeliveryName = sr.ReadLine();
        }
    }

    displayDeliveries();


}


private void displayDeliveries(){

    lstDeliveryDetails.Items.Clear();
    Console.WriteLine("Test content");
    Console.WriteLine(mainForm.myDeliveries.Count);
    foreach (Delivery d in mainForm.myDeliveries){
        lstDeliveryDetails.Items.Add(d.DeliveryName);

    }
}

有人能帮忙吗？？