C# :: Changing Quantity To List Object In Listbox Checkout

i have a program that is a Mediastore and i have 4 classes. Produkt: which is a class with a few variables that i use to add products to my List.

public class produkt
{
public string Name;
public string price;

[Code]....

then i have my Lager class which i use to add my products to my list and Listbox. This is done by having 3 textfields where i say what the Name,SerialNumber and Price of the object i created should have.

In this class i also have 2 more textfields and a button that make it possible to add a quantity of the selected listbox object of my product Class. if the item im trying to add a quantity to dosent exist i get a question if i wanna add that product and it adds that product to the list. if however the product allready exist its suposed to add the quantity with the selected amount from my textbox.

Then I have my Class Kassa which is a Form with 2 Listboxes. The first listbox share the same List as the one in my Lager class and the other listbox is the listbox which i use to take items from my produktlist and put it in my checkout "basket" then i am suposed to be able to choose one of these items from my checkout basket put the amount i want of that item into a textfield called KvantLEv and press the checkout button to be able to simulate a checkout and then this selected item's quantity is suposed to be lowerd by the specified amount and is to be removed from the checkoutlistbox but this aint working... this is my checkout function so far

private void cashout()
{
produkt p = new produkt();
int a = VaruKorg.Items.Count - 1;

[Code]....