Cannot pass string parameter to stored procedure C#

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C#

SQL

stored-procedure

Hello
I searched through this site and found some topic about my problem but still cannot make this work....
I am simply trying to retrieve data from SQL Database using a stored procedure.
I am passing one parameter that is a SqlDbType.Varchar(50) type, but get back an SQL error:

Procedure or function 'WyszukajPrzesylki' expects parameter '@Nazwisko', which was not supplied.

What am I doing wrong? Store procedure works if I test it in SSMS ...
It even works when I type

SqlCommand com = new SqlCommand("WyszukajPrzesylki @Nazwisko = Example", con);

You are my last hope guys... I've already lost 2 days with this problem and cannot get any further... don't have any problems with inserting and updating records using c# ... just this....

So here is the code of SP

ALTER PROCEDURE [dbo].[WyszukajPrzesylki] 
	-- Add the parameters for the stored procedure here
	@Nazwisko varchar(50)
    AS
    BEGIN
	-- SET NOCOUNT ON added to prevent extra result sets from
	-- interfering with SELECT statements.
	SET NOCOUNT ON;

    -- Insert statements for procedure here
	-- SELECT * FROM Przesylki WHERE (NazwiskoAdresata = @NazwiskoAdresata)
	SELECT * FROM Przesylki WHERE (Przesylki.NazwiskoAdresata = @Nazwisko)
    END

and action of the button:

SqlConnection con = new SqlConnection(Properties.Settings.Default.Monitoring_PrzesylekString1);
          SqlCommand com = new SqlCommand("WyszukajPrzesylki", con);
          com.CommandType = CommandType.StoredProcedure;
          SqlParameter parametrNazwisko = new SqlParameter("@Nazwisko", SqlDbType.VarChar, 50);
          parametrNazwisko.Value = "Dziubak";
          com.Parameters.Add(parametrNazwisko);

          SqlDataAdapter ad = new SqlDataAdapter(com.CommandText, con);
          DataSet ds = new DataSet();

          ad.Fill(ds, "id");
          con.Close();
          DataTable datatableA = ds.Tables[0];
          dataGridView1.DataSource = ds;
          dataGridView1.DataMember = "id";