drag and drop with two boxes

Question

Hi I'm making a code which I can drag and drop the text between two boxes. In my code only the listbox1 works but the listbox2 is not. Another thing is if I add several text on my listbox and select any text in my listbox I'm getting an error: InvalidArgument=Value of '-1' is not valid for 'index' Parameter name: index. can you please help me look where should I change the value of index into -1? Thanks

I'm quite stuck-up here: By the way, here is my code:

 namespace ListBoxDragandDrop
{
public partial class Form1 : Form
 {
    public Form1()
    {
        InitializeComponent();
        //Add for the drag and drop
        this.listBox1.MouseDown += new MouseEventHandler(this.listBox1_MouseDown);
        //public DragDropEffects DoDragDrop(object data,
        //DragDropEffects allowedEffects);
    }

    private void cmdAdd_Click(object sender, EventArgs e)
    {
        string yourInputText;
        yourInputText = textBox1.Text.Trim();

        if (yourInputText.Length > 1)
        {
            listBox1.Items.Add(yourInputText);
            textBox1.Text = string.Empty;
        }

        else
        {
            MessageBox.Show("Bitte schreiben Sie Ihre Texte im Feld auf");
        }
    }

    private void cmdDelete_Click(object sender, EventArgs e)
    {
        int listBoxSelectedItem = listBox1.SelectedIndex;
        listBox1.Items.RemoveAt(listBox1.SelectedIndex);
        //Selected "False" in the Enable Properties 
        cmdDelete.Enabled = false;
    }

    private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (listBox1.SelectedItem != null)
        {
            cmdDelete.Enabled = true;
            //Added if you use the btnToRight
            btnToRight.Enabled = true;
        }
    }


    private void listBox2_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (listBox2.SelectedItem!=null)
        {
            cmdDelete.Enabled = true;
            //Added if you use the btnToLeft
            btnToLeft.Enabled = true;
        }
    }

    private void btnToRight_Click(object sender, EventArgs e)
    {
        if (listBox1.SelectedItem!=null)
        {
            listBox2.Items.Add(listBox1.SelectedItem);
            listBox1.Items.Remove(listBox1.SelectedItem);
            //Add this to disable the btnToRight unless you select an item 
            //from listbox1
            //Set "Enable" in the Properties as false
            btnToRight.Enabled = false;

        }
    }

    private void btnToLeft_Click(object sender, EventArgs e)
    {
        if (listBox2.SelectedItem != null)
        {
            listBox1.Items.Add(listBox2.SelectedItem);
            listBox2.Items.Remove(listBox2.SelectedItem);
            //Add this to disable the btnToLeft unless you select an item 
            //from listbox2
            //Set "Enable" in the Properties as false
            btnToLeft.Enabled = false;

        }
    }   


    //For the Drag and Drop set the destination control "Allow Drop" to True
    //Destination Control is where you drag drop an item
    //then add an event handler, this can be seen in the initialization
    //then add the event MouseDown, here set the Events of listbox1
    //public DragDropEffects DoDragDrop(object data,DragDropEffects 
    //allowedEffects);      

    private void listBox1_MouseDown(object sender, MouseEventArgs e)
    {
        if (listBox1.Items.Count==0)
            return;

        int index = listBox1.IndexFromPoint(e.X, e.Y);
        string s = listBox1.Items[index].ToString();

        DragDropEffects dde1 = DoDragDrop(s, DragDropEffects.All);

        if (dde1==DragDropEffects.All)
        {
            listBox1.Items.RemoveAt(listBox1.IndexFromPoint(e.X, e.Y));
        }

    }

    private void listBox2_DragOver(object sender, DragEventArgs e)
    {
        e.Effect = DragDropEffects.All;
    }

    private void listBox2_DragDrop(object sender, DragEventArgs e)
    {
        if (e.Data.GetDataPresent(DataFormats.StringFormat))
        {
            string str = (string) e.Data.GetData(DataFormats.StringFormat);
            listBox2.Items.Add(str);
        }
    }