Transaction count after execute indicates a mismatching number of begin and commit

Transaction count after EXECUTE indicates a mismatching number of BEGIN and COMMIT statements. Previous count = 0, current count = 1.

USE [db_my_database]
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER PROCEDURE [dbo].[data_add]
	@ID int OUTPUT,
	@TYPEID int = null OUTPUT,
	@name nvarchar(50),
	@code nvarchar(50),
	@type nvarchar(50)
AS
BEGIN transaction
	SET NOCOUNT ON
	SET @TYPEID = (select id from category where name = @type)

	insert into mytable(name, code, type)
	values (@name, @code, @TYPEID)
	SET @ID = IDENT_CURRENT('mytable')
        RETURN @ID
commit transaction

if @@error <> 0
	begin
	ROLLBACK transaction
end

Dim command As SqlCommand = New SqlCommand("data_add", conn)
command.CommandType = CommandType.StoredProcedure
command.Parameters.Add("@ID", SqlDbType.Int).Direction = ParameterDirection.Output
command.Parameters.Add("@name", SqlDbType.NVarChar).Value = "name here"
command.Parameters.Add("@code", SqlDbType.NVarChar).Value = "code here"
command.Parameters.Add("@type", SqlDbType.NVarChar).Value = "type here"
command.ExecuteNonQuery()