Mine

 //save player profile
                cmd.CommandText = "proc_insert_update_PAR_Profiles";
                cmd.CommandType = CommandType.StoredProcedure;
                cmd.Connection = conn;
                cmd.Parameters.Add(new SqlParameter("@Id", "0"));
                cmd.Parameters.Add(new SqlParameter("@UserId", dt.Rows[0]["UserId"]));
                cmd.Parameters.Add(new SqlParameter("@AccessId", dt.Rows[0]["AccessId"]));
                cmd.Parameters.Add(new SqlParameter("@MembershipId", dt.Rows[0]["MembershipId"]));
                cmd.Parameters.Add(new SqlParameter("@NextPayDate", dt.Rows[0]["NextPayDate"]));
                cmd.Parameters["@Id"].Direction = ParameterDirection.Output; //this line causes error
               dt.Rows[0]["AccessId"].ToString() + " " + dt.Rows[0]["MembershipId"].ToString() + " " + dt.Rows[0]["NextPayDate"].ToString());
                cmd.ExecuteNonQuery();


                if (!cmd.Parameters["@Id"].Value.Equals(DBNull.Value))
                    playerID = Convert.ToString(cmd.Parameters["@Id"].Value.ToString());



ALTER PROCEDURE [atomic].[proc_insert_update_PAR_Profiles]
(
	@Id int output,
	@UserId varchar(32),
	@AccessId int,
	@MembershipId int,
	@NextPayDate datetime
)
AS
Begin

	UPDATE	PAR_Profiles
	SET		UserId			= @UserId,
			AccessId		= @AccessId,
			MembershipId	= @MembershipId,
			NextPayDate		= @NextPayDate
	WHERE	Id				= @Id
	
	if(@@ROWCOUNT<=0)
	BEGIN
		INSERT INTO PAR_Profiles
		(UserId,AccessId,MembershipId,NextPayDate)
		VALUES
		(@UserId,@AccessId,@MembershipId,@NextPayDate)
	END

	SET @Id = SCOPE_IDENTITY()

End