raffle arraylist validation

I'm making a raffle c# program where random of 1-10 numbers will be drawn and put it on ArrayList and if the number is already drawn then it should not be place in the array...my problem is even if I validate it, it still added on the array.

Here is my code:

Console.WriteLine("RAFFLES");
ArrayList array = new ArrayList();
Random rnd = new Random();

ret: Console.Write("Press 1 to draw");
int draw = int.Parse(Console.ReadLine());

switch(draw)
{
     case 0: break;
     case 1:

         if (array.Contains(rnd.Next(1, 11)))
         {
             Console.WriteLine("Already Exist");                        
         }
         else
             array.Add(rnd.Next(1, 11));

         goto ret;

     case 2: 

         foreach (var a in array)
            Console.WriteLine(a);
          break;
}