List box selected item

Hi,

1. I have two List box A and B put in Update panel
2. I would like to move selected item from A to B on button click event.
3. I followed this code to move A to B
ListItem liFieldName = new ListItem();
liFieldName.Text = lsbA.SelectedItem.Text;
lsbB.Items.Add(liFieldName);
4. My problem is when i select any item from A, The first item of A olny moved to B List box.
5. And also How can I remove the selected item?
5. Any idea ?

Let me know 

Thanks
Sabarish
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