Different problems with my application

Question

Hi

1)
I'm trying to display a list in a listbox. But I only see the last entered item in the listbox.
This is my code:
[code]
                List<BurstKlasse> Burst = new List<BurstKlasse>();
                Burst.Add(new BurstKlasse(lengte,CPU_Burst));
                listBox2.DataSource = Burst;
[/code]

2)
My second problem is that I can't uncheck the radiobuttons. If the user has checked it, I can not uncheck it when he presses a button.

3)
In one way or another I can't put a selected item from a combobox in a variable and then add it in the list. The code I have is:
[code]
int PNr = int.Parse(textBox1.Text);
                int PAankomst = int.Parse(textBox2.Text);
                String PNaam = textBox3.Text.ToString();
                //ProcesKlasse.PState Pstatus = comboBox1.SelectedValue.ToString();

                List<ProcesKlasse> Proces = new List<ProcesKlasse>();

                Proces.Add(new ProcesKlasse(PNr, PAankomst, PNaam/*, Pstatus*/));
                listBox1.DataSource = Proces;
[/code]

The ProcesKlasse is a class not in the form but in the same solution.

I would very pleased with any answers!
Thank you

Annieken