What is wrong with my update part after click buy button? Tblproducts does not updated and get error procedure or function 'SP_updateproducts' expects parameter '@PID', which was not supplied.

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER PROCEDURE [dbo].[SP_UpdateProducts]
(
@PID int,
@Quantity int
)
AS
BEGIN
SET NOCOUNT ON;
UPDATE tblProducts SET PQuantity = @Quantity WHERE PID = @PID
END

create table tblProducts
(
PID int identity(1,1) primary key,
PName   nvarchar(MAX),
PPrice money,
PSelPrice money,
PBrandID int,
PCategoryID int,
PSubCatID int,
PGender int,
PQuantity int,
PDescription nvarchar(MAX),
PProductDetails nvarchar(MAX),
PMaterialCare  nvarchar(MAX),
FreeDelivery int,
[30DayRet]  int,
COD       int,
Constraint [FK_tblProducts_ToTable] FOREIGN KEY ([PBrandID]) REFERENCES [tblBrands] ([BrandID]),
Constraint [FK_tblProducts_ToTable1] FOREIGN KEY ([PCategoryID]) REFERENCES [tblCategory] ([CatID]),
Constraint [FK_tblProducts_ToTable2] FOREIGN KEY ([PSubCatID]) REFERENCES [tblSubCategory] ([SubCatID]),
Constraint [FK_tblProducts_ToTable3] FOREIGN KEY ([PGender]) REFERENCES [tblGender] ([GenderID])
)

<pre> protected void btnBuyNow_Click(object sender, EventArgs e)
    {

        Int32 UserID = Convert.ToInt32(Session["USERID"].ToString());

        //This will add +1 to current quantity using PID

        int PID = Convert.ToInt32(Request.QueryString["PID"]);

        using (SqlConnection con = new SqlConnection(CS))
        using (SqlCommand cmd = new SqlCommand("SP_UpdateProducts", con) { CommandType = CommandType.StoredProcedure })
        {
            DataTable dt = new DataTable();
            using (SqlDataAdapter sda = new SqlDataAdapter(cmd))
            {
                sda.Fill(dt);
            }

            foreach (DataRow row in dt.Rows)
            {

                int myQty = row.Field<int>("Qty");
                int PQuantity = row.Field<int>("PQuantity");
                if (myQty < PQuantity)
                {
                    int updateQty = row.Field<int>("Qty");
                    cmd.Parameters.AddWithValue("@Quantity", PQuantity - updateQty);
                    cmd.Parameters.AddWithValue("@PID", PID);
                    cmd.ExecuteNonQuery();

                    con.Open();
                    Response.Redirect("OrderConfirmation.aspx");
                }
            }
        
    }
    }

tblProducts does not updated and get error Procedure or function 'SP_UpdateProducts' expects parameter '@PID', which was not supplied.