Disposing of list and listbox items
===

Hey I have a really annoying problem I have a list of doubles and a list box. A user can enter a value into a textbox and then click EnterValue.

    List<double> listDouble = new List<double>();

        private void EnterValue_Click(object sender, EventArgs e)
        {
            //convert input to double
            listDouble.Add(Convert.ToDouble(textBox1.Text));
            textBox1.Clear();
            //clear existing items
            listBox1.Items.Clear();
            // clear any existing list items
            for (int i = 0; i < listDouble.Count; i++)
            {
                listBox1.Items.Add(listDouble[i]);
            }
         }

I then have another button the user can click which will sum that list of doubles entered.

        private void button2_Click(object sender, EventArgs e)
        {
            listBox1.Items.Clear();
            CalculateSumOfList.ServiceReference1.Service1SoapClient client = new CalculateSumOfList.ServiceReference1.Service1SoapClient();
            CalculateSumOfList.ServiceReference1.ArrayOfDouble arrayOfDoubles = new CalculateSumOfList.ServiceReference1.ArrayOfDouble();
            arrayOfDoubles.AddRange(listDouble);
            string result = client.CalculateSum(arrayOfDoubles);
            label1.Text = result;
            //for (int i = 0; i < listDouble.Count; i++)
            //{
            //      listDouble.Remove(i);
            //}
        }

The problem here is that when the user enters a value it is added to the list which is fine, when then user enters another number the list displays fine, and when the user calculates the sum of the list the value is correct. But after that if the user then goes back to add more numbers to the list the "old" list is appended onto the end?

Ive tryed every means to dispose of that "old" list after the calculation has been done. But nothing works. Which ofcourse then ruins the second attempt.